Hi Phyllis,
Good Day. Hope everything's fine. Im sorry to hear about your Gmail to Outlook syncing problem. Let's try to do some steps, and hope to resolve the issue.
First, let's double check the "Show in IMAP" in Gmail again. On your Gmail Go to Settings> Labels > make sure all labels is "Show in IMAP". Switch on and off for a force refresh.
Second, Refresh and subscribe the IMAP folders in Outlook. To do this right-click the top folder for the Gmail Account > IMAP Folders > Query > select the missing folders > Subscribe. Right-click the account >and Update Folder List. Sometimes new outlook versions can take a few time before a label will show-up.
Third, try checking nested labels, root folder path and special characters. Sometimes it don't map these labels cleanly in Outlook. Try to move a missing label temporarily to the top, then resync and wait if it will appear. If still fails, try setting the IMAP Root folder path for the account to Gmail. Open File>Account Settings > Advanced > Root folder path, restart outlook.
Note: Changing the root path forces a resync, back up first any local-only folders before doing this procedure.
Last, Sign-out and re-link your gmail account in your Outlook App. Also, you can remove and add the account again to have a fresh sync again.
Feel free to message me again if nothing works. Have a great day.
Sincerely,
Jhun