Among some Spanish and French speakers, it’s acceptable to give a person a middle (or second given, however they characterize it) name of the opposite sex, for example “Jose Maria (Joseph Mary) Lopez” would be a guy. A girl could be “Maria Jose” Lopez.
Sasha is the Russian nickname for Alexander, but here it sounds feminine.
I don’t know about Frank, but Fran as a nickname now sounds like a shortening of Frances more than Francis, unless you mean Fran Tarkenton
John Wayne’s real first name was Marion, but it sounds too much like Marian to be used as a boy’s name now. Maybe there are even girls named Marion now.
That was so Last Year though! 
We have a 70-ish female friend of the family named Michael. Her father was disappointed she wasn’t a boy, they didn’t have a girl’s name picked out, and her mother was out of it after giving birth, so her dad named her Michael anyways.
I have an uncle named Leslie, he goes by Les.
I know of several male 30-somethings named Robin and Kelly. They’re all hockey players from Canada, if that means anything.
Male customers at work named Lynn, Kim, and Dana. All are 40-50ish.
There are some female Andrews and Drews about the place.
Robin was a female character in the British “Chalet School” series of girls’ boarding school books from the 1930s. Other than that, in the UK it is mostly male. The female equivalent is Robina- shortened to Bina by the two girls I’ve known.
I have any number of patients called Caitlín- it’s pronounced Kathleen for all of them bar one- who is Katelynn, and whose mother is American.
So there you go.
I love the name Sydney for a girl (Sidney, being, of course, the masculine version- see Sidney Poitier and Sydney Poitier), but unfortunately our last name is also an Australian city, so it would be too cruel to land an Irish child with such an Aussie name.
I’m not sure I love the occupation-as- female-firstname fashion that seems to have taken hold:
Hunter
Harper
Fisher
Cooper
Archer
Baker
Carter
Fletcher
Smith
Bailey
Carver
Marshall
Mason
Sawyer
Tanner
Tyler
etc.
I mean, seriously- ‘my 4 year old daughter’s name means “one who cures animal hides”- isn’t that just darling?’
I don’t get it.
Do you have any patients called Shakira? Apparently it’s common enough in Derry and Strabane. 
But Miss Nightingale was beaten to it by Percy Florence Shelley, born six months earlier.
I was coming in to mention Ashley.
Semi-related: I had a fraternity brother named Ashley. I’d only seen one person make fun of his name. Everyone else learned from his mistake.
Another male (albeit fictional) Gail was Gail Wynand from Ayn Rand’s “The Fountainhead,” who was a tough-as-nails ex-street kid who rose to run a major newspaper (think William Randolph Hearst). I was put off a bit at first by the fact that he had such a feminine name, but by the time I finished the book it seemed perfectly natural.
The only male “Robyn” I’ve ever encountered is Robyn Miller, brother of Rand–they were the creators of the old “Myst” game.
Aren’t there a couple of young actresses now named Evan? That was only a boys’ name when I was a kid.
I know of two sisters (who graduated from college several years ago) named Drew and Devyn, the latter being an example of the common but irritating “make it a girl’s name by overlaying Ys and Ks” convention.
As for the “occupation” names, you’re missing a step. The trend is to name girls with erstwhile last names, many of which are occupation derived. This used to be done for both genders, especially where the maternal line had a prominent name - for example “Rutherford B. Hayes”. Now it seems to be a much stronger trend for girls’ names, responsible not only for names like Tanner or Mason, but also the aforementioned Mackenzie and Skylar (Schuyler), and probably many others I desperately don’t want to think about.
Heck, my own son Kendall suffers from this - he got a first name that’s really a last name, and it turns out it’s become wildly more popular as a girl’s name since the late 1980s or early 1990s (which caught me by surprise as he was born in 2003, but I had yet to meet or hear of a female Kendall until after he was born).
That would be a Barbiedall.
I heard a song once of a boy named Sue. Seems he ended up in a fight with his father or something.
alexis (aleksay) is still exclusively male in slavic countries.
the only name i can think of that went from girl to nearly only boy is douglass. they drop the second s for a more manly looking name.
There were four that astonished me. The first three have already been mentioned but not, I think, the fourth: Evelyn, Shirley, Beverly, Joyce.
In French the name Chantale used to be unisex (yes, even with the “e”) but is now almost exclusively female. There are a few (Michel(e)) that add an “e” for female and at least one (Claude) that is totally unisex.
I have a second cousin who was named Aubrey. Or maybe it was his wife who I was related to, her name was Marka. Part of a large family from NW Arkansas.
They are either very old or dead by now. It was a big family and I am not in contact with many of them anymore. But I always though of Aubrey as a kind of cool name for a guy.
Aubrey de Grey is the only Aubrey I ever heard of.
In the Byzantine Empire, during the Middle Ages, Tiffany was a shortening of the name Theophania, which was a female name. Although I suspect there has been more than one derivation for the name. In the first Tiffany Aching book Pratchett suggested a different one. Something like Wave Under Rock (Ground? Fields?)
ETA - I opened the tread with three suggestions, but they’ve already been given.
No current Shakiras- have treated one in the past. I know there is a Hannah Montana McDonagh somewhere. A friend swears there’s a 10 year old Pocahontas in the Ballymena area, although I have no first hand knowledge.
There’s at least one in Dublin too. I hoper her middle name is Dorothy.