Problems with *69 phone callback?

As I’m sure most of you know, the USA telephone code *69 works for most venues to identify the last call received on that number, announcing the digits by voice, and offering the option of pressing “1” to return the call.

Yes, I know, the CID system has numerous flaws, can be spoofed, doesn’t work for “private” numbers, etc. But I am starting to notice an oddity, and I’m wondering if anyone else has seen this, because it might be happening only on my local phone provider (Charter Spectrum), or not. It’s also possible that it is a landline fault vs. cellphone.

Sometimes, if I enter *69, instead of getting the voice message announcing the digits, I get an immediate callback initiated, but it goes to the 2nd-to-last call received, not the last call.

If the digits are announced first, that is always the last call. If the digits are* not* announced, it’s the previous-to-last call. On occasion, this has been embarrassing.

I’m guessing, but it appears that there is a short delay (~20 secs?) for the “last call” memory storage to be reset, slower than the “hangup” procedure, i.e., a telco function, not something in my local handset. Why the digits (wrong ones) are not announced first, I dunno.

Any thoughts? Observations? Confirmations?