I have never got “Sync All” to work: the app just hangs on “Updating collection 0/10” or something similar. Well, it’s not really hung, but I need to turn off the Internet connection to make it abort whatever it is doing.
Syncing individual collections works, but it is tedious if many collections have been updated, especially if they are not directly on the dashboard.
I reported this in connection with another bug, which has since been fixed, so I thought I should report this one separately, so that it should not be forgotten.