Hostile small blob becomes friendly when a friend dog is also near you. When this happens, you can only push away the blob.
You should be able to attack it with a ranged weapon, or just throw something at it, or just use a pet carrier to take it away(if you need to remove it from your base or something).
I know they are friendly if you activate a goo canister I believe, but I haven’t had too many friendly things yet in the cataclysm. The above doesn’t fix your bug, but maybe it can help in the meantime. Sorry if you already knew all that.