by Ken Task.
And when you went to
http(s)://yourserver/admin/settings.php?section=mobilesettings
as suggested earlier you saw what?
Think Moodle 3.4.x had a bug in it related. Have a 3.4.highest for testing purposes and have no such issue. But accessing the area above does produce some 'red' warnings about certificate not being valid ... uhhhh, not true.
If desiring to keep the 3.4.x you have, download locally the 3.4.x code, unzip locally, and compare what's in the unzipped archive with what's in one of your instances of Moodle on server.
On my server, error in a 3.5.x or 3.6.x. not present.
Fix? Time to upgrade?
As far as why/how that happened ... sorry, no Vulcan Mind Meld possible on this end! :|
'spirit of sharing', Ken