I'm pretty sure that's it. I had 2 polls open with the hashtag set to lock immediately. Voting had occurred as normal over the last 3 weeks. When I went to check on them after seeing this, there was no way to vote (only see who responded), so they were apparently closed.
Thanks...I was afraid of that. I suppose I can find some way to work around it, but Robert's Rules will be more difficult to enforce without separate controls.