There's a very similar-looking report in the bug tracker: https://tracker.moodle.org/browse/MOBILE-3530
It has been traced to mod_hvp and a fix is in the works.
Moodle.org
There's a very similar-looking report in the bug tracker: https://tracker.moodle.org/browse/MOBILE-3530
It has been traced to mod_hvp and a fix is in the works.