All the checks say successful but nothing ever syncs. I know my Radicale setup is working right because I am able to sync to Android via Davx5 and to my desktop via Thunderbird. I even setup Baikal as well because I read somewhere that it has iOS support, but ended up with the same issues. I can sync with Android and Desktop but not iOS.
I also had similar issues on iOS when I migrated to Baikal. Every other device was working fine.
Double check that your certificates are valid. I don't remember the exact details but Apple made a few changes somewhat recently in regards of what kind of certs are accepted on their devices.
If you're using self signed certs you have to install them manually as well, don't forget that.
I just went back to NextCloud and made it barebones (Bookmarks, Calendar, Tasks, & Contacts only) Everything still working perfectly lol. Thanks anyways though.