@MorteSorry for the ping but it would be a great start if I could see a screenshot of the area this has happened. Mostly I want to see how the traps are laid and what is around them, and how big the pit area is. Thanks
And
@Roland is correct there: what some may call the definition of insanity we call our cup of tea
Post-inital investigation update
So far all blade traps are working at bedrock on my test dedi, but there is a known issue where the damage states aren't updated until the area is left (nobody there) and came back to (i.e. they should be destroyed needing repairs but still spin like normal but don't damage anything on touch) - could that be it? Try leaving the area and coming back when you see these.