Hmm so even calling ClearLevel the state is not reset? That's weird. There may be some parameter I'm failing to reset. For additional clarity, are you doing this in Play mode at Runtime or in Edit mode or both? Thanks for your patience, I'll take a look at your repro case and get back to you.
Honestly I probably should just move the state-ful stuff out of the BoardGenerator and into a function like almost everything else. Gonna have a think about it.
best,
Matt