The Dropbox taskbar button has disappeared recently (Win11 Pro), DB is running (syncing ok, processes running in task manager) and all icons are set to show in the taskbar so it's not a taskbar config issue.
The only solution I've found suggested to this (other than the basic 'check your taskbar settings one) is uninstalling and reinstalling Dropbox but I'm very nervous about doing this as I have a VERY large archive with selective sync and I want to check the config to confirm exactly what is online only before trying the 'move archive out and back into folder after reinstalling' to avoid downloading everything. It would take days (if not weeks) to resync everything on my current connection.