Hello Krzysztof,
We are grateful for the time and effort you have put into debugging this issue.
We recommend that you keep the Mobile Content Optimization option disabled if you are using a cache plugin for mobile devices, as both optimization options can conflict with each other.
Please refer to the screenshot provided at the link below for further information: https://postimg.cc/pymsRBTk
We hope this helps!
Best Regards,
8Theme’s Team