LeePhillips1: I'll share my experience with the switchover from legacy to new Outlook, but I doubt it will be of much value to you. My primary email account is sbcglobal.net (Yahoo), not AOL. When I clicked the old to new Outlook switch, I didn't (to my recollection) get the Microsoft Cloud sync option (which is fine, because I wouldn't have chosen it).
After a few chores like choosing colors, etc., my inbox filled up. I noted that my other folders would sync (sometimes slowly) as I clicked on them, but a new feature, I guess, is the "Load more conversations" option, which appears either by itself in a folder, or after a few emails have downloaded into a folder. I guess it's individual preference whether one wants to pull all their emails into Outlook, or leave some or most of them sitting on their Yahoo/AOL/etc. account and download as needed.
Since I was primarily concerned with the magically emptying folders I'd been dealing with, along with the duplications in almost every folder, I chose not to download every last email into every Outlook folder - at least not yesterday. I may do that at some point (I have a couple of HUGE folders), but I'm now pretty confident that once I download emails into an Outlook folder, they stay there, thank God!
I also have a much less active Microsoft Exchange account I use, and again, if I recall correctly, it downloaded automatically, because I don't remember adding it to Outlook, so it must've populated itself when I clicked the "new" switch.
I was also able to populate the calendar quite easily. So far, I haven't seen any glitches or even a bump in the road. The biggest challenge now is getting used to the look of the new Outlook, and locating all the buttons and whatnot. After seeing your post this morning, I opened Outlook (I've been in and out of it a few times since I made the switch, with no detectable issues) and checked some folders, and all appears well, just as I left it yesterday.
Sorry this isn't more helpful for your situation. Maybe someone else with an AOL account will weigh in here, and/or someone can explain what might've happened re: Microsoft Cloud vs. IMAP.