I see that inside display_question_editing_page() function, "$mform->display();" is printing an empty string.
After that, "echo $OUTPUT->footer();" is not reached.
That's weird. And I don't understand why I'm the only one experiencing this issue, even after the upgrade. And it happens randomly, here are the debug messages when suddenly 'works':
13.525071 secs
RAM: 40.1MB
RAM peak: 40.3MB
Included 685 files
Contexts for which filters were loaded: 1
Filters created: 2
Pieces of content filtered: 0
Strings filtered: 0
get_string calls: 2434
strings mem cache hits: 0
strings disk cache hits: 3691
Included YUI modules: 0
Other JavaScript modules: 4
DB reads/writes: 1828/0
ticks: 1353 user: 554 sys: 41 cuser: 0 csys: 0
Load average: 0.76
Session: 7.5KB
Caches interaction by definition then store
core/databasemeta
** static persist **: 1677 / 25 / 0
cachestore_file: 25 / 0 / 0
core/string
** static persist **: 3351 / 340 / 0
cachestore_file: 340 / 0 / 0
Total Hits / Misses / Sets : 5393 / 365 / 0
This page is: General type: admin. Context Quiz: Benchmark 2012 Module 4 (context id 68). Page type question-type-multichoice.