Topic time does not accept values less than 1 hour. Has worked before, for a very long time.
Auto-close topic
Close based on last post
Try to set a value below 1 hour, say 0.25 for 15 minutes
One hour is a very long time for a heated discussion. We actively use values around 10 minutes to end our game chats. It works very well as the timer triggers when things start to cool down (our game topics get up to 1000 posts in a couple of hours).
Propose the fix to be backported to the stable channel. Reasoning: Old basic functionality broken.