I have the same issue. Been looking for months for a solution. Mine is Windows 10, Outlook, and Yahoo account. Of course, I took on a major role for a 501 c 3, and all my old emails disappeared. It has been challenging these last few months not having the history. Had to spend time cleaning inboxes to discover they come back the more you delete. So I was able to retrieve some of the last years emails for the previous event.
Another issue I am having: I open outlook, still have the limited amount showing, and do something. All of a sudden I look and my emails are "deleting". The inbox is counting down and completely empties! I give it some time and it all comes back to the 10,000 rule. I am seeing the same kind of thing on my iPhone 12 with the Mail app. I am using and all of a sudden it deletes everything. I come back and after a few refreshes, it repopulates, BUT those emails that came in during the "empty" time aren't there. Only the new ones and the previous ones.
I also am adding this note here in hopes I will be notified of a resolution! I am very tired of this issue and want my emails back. I want to be able to search via a keyword and all occurrences of that keyword appear - not just the last year. This bug is really annoying! In the past, I created folders, then outlook crashed. I retrieved my emails, but none were in the folders. Thus I quit using folders as that was a waste of time.
Any info is appreciated.