As designed When merging 2 threads, and one has a poll, the poll is no longer visible in the resulting thread.

[Jesepi]

I'd imagine this has something to do with the fact that the threads were started by separate users. I've not tested this situation with 2 threads from the same user.

While this might be a working as intended situation, or just a byproduct of how polls work, it might be worth some sort of notification that the poll will be lost, or an additional prompt asking if the poll should be attached to the new thread.

 

[ibnesayeed]

I guess, It depends upon which thread is being merged with whom. If a thread A has poll and a plain thread B is merged to it then there should be no loss but if thread A is merged into thread B then belongingness of the poll is lost because that thread id is no more there. It is my guess, I am not sure about the actual implementation though.

 

[Paul B]

See this thread: http://xenforo.com/community/threads/adding-a-poll-to-an-existing-thread.14303/

You must merge the threads so the thread with the poll is the destination thread.