Kill 5 mimics and flop

Sooooooo, I've finally given up with this task! Tried it so many times and failed. Didn't wanna give up...... But....

Playing today, get the diary again. Go to popov to do the flopper, again.

Get it on my third attempt. Punch the air in celebration. The look....... No reward rifts. Yellow portal still active, managed to hit again. Punch the air again. No reward rift!!!!!! Frustrating.

So, can I ask. Has anyone got a gold one they aren't using? Or can someone do it for me because it's frustrating me too much.