Hi,
Are these inbox emails imported from a PST file?
Can you see these missing emails if we view the email account from Gmail webmail interface in a browser?
Do you have any filter set on the subfolders? We may try to start Outlook with
/cleanviews command to reset all custom views to the default one and then see if you can see the missing emails.
In addition, we may also try to switch the sub-folder view from Hide Messages Marked for Deletion to
IMAP Messages to see the result.

Hope this helps.
Regards,
Steve Fan
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