"Seen" tag not getting synchronized

[Arjun]

Hi

I have offlineimap syncing a gmail repository that I then use notmuch on. Lately,
offlineimap has been deleting the S (Seen) flags from my gmail maildir once I change them on the maildir file using notmuch. I am running offlineimap 7.3.3.

Here is my sanitized offlineimap conf

#### Account name ####
[Account gmail-name]
localrepository = gmail-name-local
remoterepository = gmail-name-remote
maxage=300
autorefresh = 10
synclabels = yes
labelsheader = X-Keywords
ignorelabels = \Important
presynchook = UMASK=007 /usr/local/bin/afew --move-mails
postsynchook = UMASK=007 notmuch new && UMASK=007 /usr/local/bin/afew --tag --new

#### Local repository: gmail-name-local ##############
[Repository gmail-name-local]
# OfflineIMAP supports Maildir, GmailMaildir, and IMAP for local repositories.
type = GmailMaildir
# Where should the mail be placed?
localfolders = /mnt/mail/offline-imap/gmail-name
# sep = .
# startdate = DO NOT USE. See offlineimap.conf
# Propagate deletions from local to remote. Messages deleted in this repository
# won't get deleted on remote if set to "no". Default is yes.
# See sync_deletes in the RemoteExample section, too.
sync_deletes = yes
nametrans = lambda f: '[Gmail]/' + f if f in ['Drafts', 'Chats', 'Starred', 'Important', 'Spam', 'Trash', 'All Mail', 'Sent Mail'] else f

My notmuch config looks like this

database.path=/mnt/mail/offline-imap/
user.name=name
user.primary_email=name at gmail.com
new.tags=new;
new.ignore=.sync
search.exclude_tags=spam;
maildir.synchronize_flags=true
muchsync.and_tags=inbox;unread;new
built_with.compact=true
built_with.field_processor=true
built_with.retry_lock=true

Any idea what's going on here? I update tags on notmuch, it sets the S flag on the maildir file. Then when offlineimap is run, it looks like this

2020-07-25 12:03:24 INFO: Syncing [Gmail]/Chats: Gmail -> GmailMaildir
2020-07-25 12:03:25 INFO: Syncing [Gmail]/Drafts: Gmail -> GmailMaildir
2020-07-25 12:03:27 INFO: Syncing INBOX: Gmail -> GmailMaildir
2020-07-25 12:03:30 INFO: Deleting flag S from 2 messages on INBOX
2020-07-25 12:03:30 INFO: Syncing Jobs: Gmail -> GmailMaildir
2020-07-25 12:03:31 INFO: Syncing Mailing lists and newsletters: Gmail -> GmailMaildir

I'd appreciate any help.

Arjun