Update: I solved my problem. I got everything working by using this repo, but also by not using LibreWolf - looks like either I'm missing something about its setup, or syncstorage-rs (firefox sync) doesn't handle it well: I noticed that when using it I would get "ua.os.ver":"UNKNOWN" in the logs, so maybe it's related.

I'm trying to host my Firefox Sync server. I got it running using docker and with instructions from this github repo. Everything looks fine, I think... I can reach the host and I can reach the __heartbeat__ endpoint, getting this response: {"version":"0.13.6","quota":{"enabled":false,"size":0},"database":"Ok","status":"Ok"}, but nothing seems to sync!

I set it up first on my LibreWolf instance and checking the docker container logs look like this:

Oct 12 10:43:42.840 INFO Starting 1 workers
Oct 12 10:43:42.844 INFO Starting "actix-web-service-0.0.0.0:8000" service on 0.0.0.0:8000
Oct 12 10:43:42.844 INFO Server running on http://0.0.0.0:8000 (mysql) No quota
Oct 12 10:43:59.438 INFO {"ua.os.ver":"NT 10.0","ua.name":"Firefox","ua.browser.family":"Firefox","uri.method":"GET","ua.os.family":"Windows","uri.path":"/__heartbeat__","ua.browser.ver":"130.0","ua":"130.0"}
Oct 12 10:43:59.706 INFO {"ua.os.ver":"NT 10.0","ua":"130.0","ua.browser.ver":"130.0","ua.os.family":"Windows","uri.path":"/favicon.ico","ua.name":"Firefox","ua.browser.family":"Firefox","uri.method":"GET"}
Oct 12 10:44:11.178 INFO {"ua.browser.family":"Firefox","ua.browser.ver":"130.0","uri.method":"GET","uri.path":"/1.0/sync/1.5","ua.os.family":"Linux","token_type":"OAuth","ua.os.ver":"UNKNOWN","ua.name":"Firefox","ua":"130.0"}
Oct 12 10:44:11.540 INFO {"ua.name":"HTTP Library","ua.os.family":"Other","ua.browser.family":"Other","ua":"curl","uri.path":"/__heartbeat__","uri.method":"GET","ua.browser.ver":"curl","ua.os.ver":"UNKNOWN"}
Oct 12 10:44:11.756 INFO {"ua.os.ver":"UNKNOWN","uri.path":"/1.0/sync/1.5","ua":"130.0","uri.method":"GET","token_type":"OAuth","ua.browser.ver":"130.0","ua.browser.family":"Firefox","ua.name":"Firefox","first_seen_at":"1728729851747","metrics_uid":"fcdfa197568a554e5f5b0a2d05d7b674","ua.os.family":"Linux","uid":"fcdfa197568a554e5f5b0a2d05d7b67452c597ab6caf7770a423378f86d1a4c0"}

I set my sync settings to have add-ons, bookmarks and history synced. I installed some add-ons, saved some bookmarks and tried to sync with a new browser profile, then with Firefox on Fedora and Mull on Android, but nothing seems to be moving.

Any idea what more to do to troubleshoot this?