ARFoundation camere freez after ad (AdMob)

Hello. I have an application where users can add more than one AR model to the ground.
App flow is this. :
1. Open Model List
2. Select one
3. Place on the ground
4.Press "ADD/PLUS" button
5. Select another model
6. Place on the ground next to the previous model.

Some of the models are unlockable with ads. So when you selecting a model with an ad (on step 5), after watching the ad Step 6 starts, but the AR Camera is freeze. I can still interact with the model but the camera background (my real space) is freeze.

What can be the problem?
This problem happens only on IOS. Andoird works fine.
Thanks.

Please file a bug report so our QA team can have a look:
https://unity3d.com/unity/qa/bug-reporting