Very strange indeed, thank You for letting us know.
First, if You logged out of Loop then logged back in, all Your
downloaded items are wiped out so Your Visibility "Show Only
Local..." setting should definitely be Off.
Second, there are visibility filters below this option, make
sure "Loop" visibility is on.
Once logged in Loop, depending on Your library size it may take
from seconds up to several minutes before Vox syncs all initial
Loop information necessary to display Your music. Try to keep Your
iPhone awake for that time so it goes faster (or play music using
Vox if iPhone is Locked)
So please check those visibility options and try to re-login.
also it's important to use good internet connection when syncing
Loop library after login.
Awaiting for Your results!