Attack area of camp in combat not disappearing

Hi,

maybe this is old or not I don't know... but this is the 2nd time in as many adventures I get this. I did SA about 20-25 times now and this is getting me worried for the remaining ones I have.

I attack a camp and the red area remains. The combat completes as usual and the camp disappears. However as this is a blocking camp the losses are really high.

It's the first camp in the 2nd zone of Surprise Attack. I managed to get a screenshot where the camp is in combat and the red area is still there (I didn't select it before combat started).

Losing 70+ elites every time I do this adventure doesn't sound very efficient.