It's all CWTN plugins that can mount a horse, cleric, shaman, enchanter, magician, etc, at least those are the ones that affect me.
I have nothing else that mounts a horse, only cwtn. I can remove the clicky downtime and they will never mount.
this 100% never happens after paused and in a zone for a bit, it only happens upon zoning into a zone immediately, like the plugin doesn't see it's paused for a fraction, starts mounting, then re-pauses.
I notice this because when i do a travelto command, sometimes i'll have some stragglers and those are the ones that mount up when zoning in. I am 100% certain they are not mounted when starting the travelto, 100% certain they don't mount in the zone i initiate the travelto, and 100% certian it happens immediately after zoning into a new zone (just does not happen 100% of the time).