Simulacrum is stuck with boss dying animation

I'm in a simulacrum and Omniphobia is stuck in his dying animation on wave 14. I killed everything and nothing dropped, and the Wave UI box never showed up. Leaving the map and coming back shows the Wave UI box but clicking on it doesn't start the next wave.

I just had the exact same bug, with the same boss also at wave 14. I also tried to restart the game, but that didn't work either.

Same happened in 0.4.0d
wave 14/15 ... thanks GGG - I do not want to repeat this shit