I'm experiencing a very weird bug. When I put down a PolyBevel SOP and enter its viewer state, the LMB-drag doesn't work. Other shortcuts, such as Shift+LMB to add an edge to the beveled group, and scroll to change divisions, work perfectly. Only LMB-drag to change distance doesn't work.
Even more weirdly, it sometimes fixes itself. If I switch to another application, then switch back to Houdini, this issue usually goes away.
I've reported this to SideFX, but they couldn't reproduce it.