My desktop Outlook (2016) is configured as an IMAP client of Gmail.
I lovingly arrange my messages within Outlook folders. This is synced to Gmail and appears as labels.
However, (at least) two of my Outlook folders have disappeared from Gmail. The messages can still be found on the server, but they contain no labels. The labels list doesn't show the labels corresponding to folders. Searching for the folders using the "IMAP folders" from the Outlook context menu yields no results.
In short - the Outlook folders remain, the messages remain both on the server and on the client, the Gmail labels disappeared.
So, my question is: How do I "sync" the Outlook folders to Gmail and have Gmail label the correct messages, those that are stored within my desktop Outlook stores in those folders?
Edit: I noticed now that the Outlook folder names have changed to contain the suffix "(This computer only)"
Edit: Found and posted a workaround, but would love it if anyone can tell what caused this mess and how to prevent it from happening!