I typed the following sentence:
“There were numerous deferred maintenance items that were existing when the previous tenants moved in”.
Spellcheck said no. Changed to “was” and no issues.
“There was numerous deferred maintenance items that were existing when the previous tenants moved in”.
That seems wrong to me. But, hey, I suck at grammar. What say ye?
“There were numerous deferred maintenance items that existed when the previous tenants moved in”.
I suppose Spellcheck interpreted the entire phrase “numerous deferred maintenance items that were existing when the previous tenants moved in” as a singular reference. It still sounds stupid though, even if it is proper grammar which I ain’t zackly sure of. The solution is to simplify the statement.
The predicate “were” refers to the subject “items”, which is plural. So the 3rd person plural of “to be” is correct.
(that’s how I’d have explained it in English class at school)
A step in the right direction, but “that existed” is redundant and therefore unnecessary. I would say: “There were numerous deferred maintenance items when the previous tenants moved in”. Simple, tells the story. The end.
Or depending on what you want to emphasize, it could be completely reworded to something equally simple like “When the previous tenants moved in, there were numerous outstanding maintenance tasks that still had not been done”. Why do people always want to dress up these things with decorative phrases like “that existed”?
As for the OP, I don’t know what “spellcheck” you were using or what the hell it was thinking, but it was completely wrong.
Yes, clearer.
I was not trying to dress anything up. I have a home owner who is trying to charge the previous tenants for things that were not their responsibility so I felt important to stress to him these item “existed” previous to their moving in. Maybe my grammar wasn’t the best, but I admitted it’s a weakness of mine in the OP.
That said, I appreciate your input on cleaning up the construction and will use it.
Sorry, no rudeness intended. I guess my mind was still on the Pit thread about “Phrases/terms that aggravate the hell out of you” in which I was particularly scornful of “biz-speak”, which really does dress things up to a sometimes comical extent. In point of fact, including a redundancy like “that existed” may be perfectly fine if you need to emphasize that aspect of the situation. Its redundancy from the neutral standpoint of good style is less important than making the main point that you want to communicate.
Incidentally, I think your last post was clearer about the whole situation than any of these grammatical nitpicks. Why not include something like what you just clearly and simply said, “I want to stress that these maintenance items existed before the previous tenants moved in”. Plain speaking is better than erudite grammatical correctness in these situations. 
I’m at work. It’s whatever comes on the PC.
Ha ha, I got a chuckle out of that.
Yes, what makes the sentence structure feel awkward is the two verbs “There were… that existed…”. An alternative would be to kill “there were”, allowing the emphasis that OP was looking for:
Numerous deferred maintenance items were already present when the previous tenants moved in.
I asked my GF, who is a professional editor and scary good at grammar…take my word for that or not…here is her answer when I asked her:
“items” is clearly plural, so “were” is correct. Period, end of story.
I put your original (correct) sentence into Microsoft Word and it did not flag it for grammar. Whatever you use at work is crap.
In the interest of brevity there is no need to say that the “outstanding” tasks had “not been done”. If they had they would not have been outstanding.
“When the previous tenants moved in, there were many outstanding maintenance tasks."
Very true. I guess I was unconsciously doing the thing I talked about earlier – using redundancy for emphasis. As I noted above, that can be justifiable and effective. Depending on the intent of the statement, technically “good” writing that a schoolteacher would approve of (or, “of which a schoolteacher would approve” 
) is not necessarily the most effective writing for a particular purpose. Example: “We shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender”. Now, would you say, for heaven’s sake Winston, just say “We shall fight them everywhere” and be done with it?
Ah, but that could mean the maintenance tasks were totally awesome.
I think your rewording (at least without any additional context) makes things ambiguous.
The sentence as originally stated means “There were numerous deferred maintenance items. They existed when the previous tenants moved in.”
Your rewording could still mean this, or it could mean “There were numerous deferred maintenance items when the previous tenants moved in, but they all have since been remedied.”
No, unless I’m misunderstanding you. “That existed” adds no new information. As @Riemann correctly points out, “There were …” already conveys the fact that these things existed, and so “that existed” is redundant. Neither version implies anything about whether the defects were subsequently repaired or not.
Repairs were needed when the tenants moved in.
I am guessing that the reason the spell/grammar check flagged the sentence is that it interpreted were/were as a double subjunctive. It probably had difficulty with the sentence syntactically, because of the redundancy, and looked at it semantically; doing that would cause it to see “There were” as introducing a hypothetical, but then there is another verb that also appears to be dealing with a hypothetical. You need only one of the verbs in a sentence like this to be subjunctive.
People very commonly say things like “I would have gone if we would have taken a cab.” That’s wrong, because you don’t need “would have” twice. You just need to say “I would have gone if we had taken a cab.”
Now, obviously, that is not what is wrong with the OP’s sentence. What wrong is the redundancy. But the computer, instead of seeing the redundancy, is seeing “were” twice, and thinking it’s a double subjunctive. I’m not sure how the computer does that-- it probably has some hierarchy of errors based on common occurrences, and assumes that the more common error has been made rather than the less common one when it isn’t sure. Or maybe it is biased to flag true errors of grammar, like the use of the subjunctive, over errors that make the writing unclear, but are actually errors of usage or style.
My grammar/spell check always flags the less common uses of effect and affect, where effect is a verb, and affect is a noun.
Gosh! I wish I could talk like that.