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For me the following instructions solved the mission and mobile bug:
First of all, you need to have the original gameconfig!
If you don't have the original one, delete "PlayGTAV.exe" and "GTA5.exe". After that, start "GTAVLauncher.exe". It will download the Update.rpf again, which the original cameconfig is included!

1. In the original Gameconfig, search for the Line "APP_INTERNET" [ <StackName>APP_INTERNET</StackName> ] and Copy the Value of it.
2. Open this (modded) Gameconfig, search for the same line and paste the Value of the original Gameconfig.
3. Go back to the original Gameconfig and search for the Line "MISSION" [ <StackName>MISSION</StackName> ].
4. Again, copy the original Value of the Line (at number 3) and paste it into the this (modded) gameconfig.

I hope it helps :D Have a good day guys!
(Sorry if the English is bad, I'm from Germany ¯\_(ツ)_/¯)