Using mbsync/isync 1.4.0 as of 2022-04-02.
mbsync is a IMAP mail sync program that I'm using in replacement of OfflineIMAP.
Locally created messages are not pushed from slave to master
I use to save my sent messages in INBOX, so I can keep track of messages waiting for an answer. For some reason, yet while setting mbsync up for the first time, those messages (created from mutt) were not being pushed back to Master (mbsync name for the IMAP server).
I know it looks stupid, but simply deleting the problematic mailbox (in my case, INBOX) and retrieving it again solved the problem. It may be happened because I changed many configuration settings many times while setting up the program.
mbsync only syncs INBOX, not other folders
Patterns * (or possible variations) in the channel
Channel Example-channel Far :Example-Remote: Near :Example-Local: Patterns * Create Near Expunge Both SyncState *