To make a long story short: I provided what in my eyes was a bug fix.
The problem being using the custom menu in a multi language Moodle installation.
Moodle version 2.7 shows the custom menu when it was configured with code as instructed in Site administration - Appearance - Theme settings - Custom menu items
Moodle version 2.8 and further stopped showing the custom menu.
I was kindly asked by the Moodle HQ developer John Okely to open this forum thread, which I gladly do, of course.
In my opinion it is not a usability issue, given the same custom menu code triggers different behaviour on Moodle 2.7 versus higher versions.
But I might miss a point.
Also, it is safe to say some other fixes and issues happened in the same field of multiple language custom menu, which may have interfered.
Please share your thoughts here.
Let me append some sources:
German custom menu in Moodle 2.7
German custom menu in Moodle higher than 2.7 with the fix provided in https://tracker.moodle.org/browse/MDL-53224
German custom menu in vanilla Moodle higher than 2.7 (note the missing pull down menu trigger on "Schnellzugriff")
Connected tracker issues:
https://tracker.moodle.org/browse/MDL-46652
https://tracker.moodle.org/browse/MDL-49655
https://tracker.moodle.org/browse/MDL-53224
Previous forum thread: (Thanks Sam Hemelryk, PJ King) https://moodle.org/mod/forum/discuss.php?d=270675
Best regards
Luca