Thanks to the instructions from Harrow.4862 I was able to do it with a griffon.
Here's the video footage, which may be helpful:
Requires the high vault mastery for springer and aerial finesse mastery for griffon. I also use bond of faith; I think it's possible to succeed without this, but it really helps.
Still, such a workaround should only be a temporary necessity, and is still not feasible for many players due to requiring a griffon as well as several masteries.
That a bug like this is not fixed after almost a week is surprising, but could be excused given certain circumstances; the fact that no one from ArenaNet has even acknowledged that this bug is treated as a high priority and that they are looking for a fix, is quite frankly inexcusable.