- Play the Wave Defense scenario, and buy some upgrades.
- Lose to biters overrunning your factory.
- Start a new round in the same session.
- You still have the upgrades you bought in the previous round.
I suspect this was introduced in 0.18.30 when fixing this bug, since it's also related to resetting upgrades.
I encountered this in multiplayer, and haven't tested singleplayer.