you may wanna give more information... which items did you use, were any commands involved... this kinda stuff.
i think this works as intended, its a mechanic against overusing trades
its a feature, not a bug.
i would say it works as intended, if they could we would have an inconsistency issue, on the other hand its probably worth taking a look at all mobs being able to pathfind in said situation
staff only accepts bugreports in english^^