Allays break their lead tethered to fences.

Problem: I have some allays strategically placed here and there and attached to fence posts with leads. Occasionally (though I cannot seem to find exactly what recreates it) when I've left the area that has Allays I'll see one flying around me, only to back track and find it's lead laying on the ground at the point of breakage (like tethered animals do if you run too fast). But fence posts do not run too fast. I've never had this happen with ANY other animal. Tamed, wild, or trying to follow me because I'm holding it's favorite food. Even the fastest of horses do not break their leads whilst attempting to get my yummy golden carrots.
And it keeps happening. It wasn't a one time event. It doesn't happen all the time, but it does repeat itself. I have even lost one of my precious (yet to be breedable) allays 😞