An anecdote for the pile.
Opened my SPG AmEx early December. $1k limit. Used it heavily to get the 75k SUB, making several mid-cycle payments along the way. I also have a Plat (opened November 2018) and am putting about $5k a month through it.
Requested a CLI online ~65 days after the account opened. Got 7-10 day message. Received the letter today saying it was declined because "Your account must be open for at least 60 days." Given I was absolutely certain of my account opening date, I thought that was odd, so I called. The representative confirmed that my online request was made AFTER the 60 day mark, so there was some kind of glitch. I doubt the glitch is limited to just me, so that's something for others to keep in mind if you get that message.
He offered to try again while he had me on the phone. I said sure, and requested a $15k increase (my Barclays limit is $50k, and I'd very much like it if they weren't my only high-limit revolver). They approved the request for - you guessed it - a $2k increase for a total of $3k. Baby steps, I guess. I'm just glad to be back in with AmEx and building a good relationship after decades on the notorious blacklist. (More on that here and here.)
FICO is about 710 (I have a couple lates from early last year). Income ~500k.
EDIT: Forgot to mention that I asked the rep, "So when can I ask again? Six months?" And he said "Yes, exactly... well, you can ask again in 4 months to be honest with you." Take it with salt, of course... FWIW.
EDIT 2: Also forgot to mention that I noticed this past weekend that I am now pre-approved for all of their cards (this was not the case when I checked in late January – back then, I was pre-approved only for the Delta and Hilton cards). Although interestingly, today I'm pre-approved for all EXCEPT the Green Card. 🤣
And good luck feel better 
