iphoneX wireless connectivity (wifi, mobile data) acting strange

Dear Community,

On my iphoneX using ios 13.4.1, most of my apps run perfectly well with WiFi or mobile data. However, some apps cannot run with wifi and some other apps cannot run with mobile data.

For those not running with wifi, I get the following error message: Wi-Fi is turned off for "app" You can turn on Wi-Fi for this app in Settings. The problem is that I do not have the option to turn on or off wifi for individual apps.

For those not running with mobile data, I get the following error message: Mobile data is turned off for "app" You can turn on mobile data for this app in Settings. When I do so, iphone turns mobile data off again by itself.

I have called several times apple support and followed below instructions:

-delete and reinstall apps

-turn off and on plane mode

-reboot iphone

-delete company profile

-reset network settings (3 times)

-reset completely iphone and install as new (2 times. 6 hour process each time to re-install all apps)

None of the above actions solved the problem.

Last detail: I bought my iphone in France and I use it in China.

I hope this community will be able to help me solving this issue apple support has not been able to manage so far.

Thanks