*** I have an update for all who are interested ***
As has become clear, Microsoft seems to be sweeping this under the rug, so I would not be surprised if no other updates are given to this forum. However, I'll give an update based on what I was told.
I'll go ahead and tell my story. I had an open note final exam the next day and I realized some critical notes were gone. I posted to this forum and then contacted my university's IT support. Fortunately, my school's IT is very competent and raised an urgent ticket with Microsoft. Somebody from Microsoft support called me within a few minutes and tried to guide me through the "fixes" that were provided on this forum (which obviously do not work). He also thought they may have been somehow deleted, so he tried to check a "second level" recycling bin only available to them and did not find my notes. I was told they were going to investigate further, but I should not expect an update for at least a day. Unfortunately, I was forced to take my exam without access to these very important notes.
Fast forward to today, I set up a Teams meeting with a Microsoft Premier Support Engineer. I called in, shared my screen, and he once again tried to see if I could find my notes on my end (it's pretty clear at this point that none of us can find our notes). We talked for a while and he said that it seems that our notes were not stored to their servers correctly since my data does not appear on his end either. I pressed him further to see if they could retrieve my missing data. He said that given the fact the data did not actually store to their servers, it seems like the data is likely permanently gone and will probably not be able to be retrieved since, again, it was never encoded/backed up onto their servers in the first place. I asked if there is anything else they could possibly do (like bring this to the attention of another level of engineer), and he responded that the only other option available to him is to submit an internal "request for review" for my case to see if any other solutions could be found. Obviously, I asked him to go ahead and do that. I also asked if Microsoft had at least told other customers about what is going on, and he said that because this seems to have only affected a "small number" of users, as of now, they are not planning on going public with this issue since the issue is "not happening anymore." In other words, people no longer seem to be losing their notes, they think this didn't affect that many people, and therefore, in their eyes, the issue is "resolved" and there is no need to announce anything.
I know I suggested this before, but now it seems more clear that this needs to be brought to people's attention as well as be put on Microsoft's radar (in case it somehow isn't already). I would suggest if you have not contacted Microsoft support with an urgent ticket through your business/school's IT or admin account, you should do so immediately as I did. Also, if anybody's business or organization has any way of spreading this through social media or the ability to make some type of announcement to a large following, I think that would be very effective at putting more pressure on Microsoft to try to find lost data or at least force them to publicly acknowledge this issue.
Sorry I couldn't get anymore info besides this. Hope this helps all who were looking for an update and I wish I didn't have to be the bearer of bad news.