I hope the description in that post is clear, but if there are any questions please let me know. I'd be happy to help solve this problem or understand what's causing it if I'm doing something wrong instead.
This issue has not been updated and has been submitted internally to icm252824185. engineers are still working on overcoming this issue and it seems to be a Dynamics issue , maybe Dynamics is changing the iframe in both cases setting. Please follow the workaround provided first and I will give you feedback here if there is any update, sorry for the inconvenience.