Ichor Pump destroyed without taking damage from mops

At first i thought it was my mistake but i got this a few times now:
when defending the pump (seeems to appear most if 4+ tendrils are spwaning)
and my towers are up no mops near the pump sometimes it just says "pump destroyed" and ends the event.

just happend and this time im 100% sure there where no mops near the pump.
idk what this is and think it only appeared in blighted maps for me but i could be wrong. as i said the first few times i thought i overlooked some mops/tendril or what ever

Just happened to me as well. Pump is even still intact as seen in this screenshot:

https://imgur.com/0W6eOQK

Very frustrating considering the current prices of blighted maps.