I've been using the Firefox browser on my devices for the past couple of months (Windows 10, MacBook Pro, iPhone), enabling the Firefox Sync feature on each. The sync seemed to be working, as far as I could tell, although I was only paying attention to open tabs and bookmarks. But last week, I installed a few new browser extensions on the Windows device, including the official extensions, ''Facebook Container'' and ''Multi-Account Containers''. Since then, I've received notices to sync my devices. I went to to my devices and verified that the sync feature was working. (It appeared to be, but I may have missed something that confirmed it.) Then yesterday, I received an email titled, "Final Reminder: Complete Sync Setup." Again, I looked at my devices, and I'm not noticing an obvious problem. '''Do these messages indicate that something is not syncing properly? Are these messages a result of the container-related extensions that I installed?'''