Although I believe I’ve encountered this other places, I know for sure there is a huge stretch of fence with this bug in Zvir.
In the large field on the northern side of Zvir there are (I believe two) rows of the farm style fencing. The one that is made of white/light grey posts and not quite waist high.
For a large section of at least one of those fences the vaulting is bugged. It’s the fence that is a couple hundred meters north of the water pump and runs roughly east to west. There is a gap in this fence that I am forced to use near the western edge of the fence. Trying to vault this fence in the uphill direction makes the character jump instead, but you can’t actually clear the fence. IIRC often times your character doesn’t appear to jump, but the audio cue and resulting stamina loss is consistent with jumping.
When attempting to vault in the downhill direction your character actually jumps the fence instead of doing the vault animation.
Again IIRC, this bug is also on other sections of fencing in Zvir, and other places as well. My character vaults this same fence style in other sections of Zvir without issue. This was on official servers 6811.