Yeah, same problem here, but I don’t have any plugins that I can deactivate to get it to work.
WP 3.5 also.
I’m having a possibly similar problem with the Pages created by the Events Manager plugin. I can select the bbPress options, but if I update an event, or select them directly when creating a new event, after it’s updated, the check box and all bbPress settings are unmarked again; also no topic is created in the forum I selected. I wonder if the fact that the events also have future dates might be the reason.
WP version: 3.4.2
Events Manager version: 5.2.5
bbPress Topics version: 1.4
