a couple things I personally would do;
- try to verify game files to check if there might be something corrupted; opening Steam > right click to ETS2 > Properties > Installed Files > Verify integrity of game files
- make sure latest drivers are installed
- press "WIN key + R" type %programdata% and look for the file "TruckersMP" and delete it
- navigate to C:\Program Files\ and delete the file "TruckersMP Launcher"
- Reinstall TruckersMP
- delete non-supported mods, maybe you have a few? just launch ets2 and deactivate them under mod section before launching truckersmp
- launch TruckersMP with directx 64-bit
- close third-party programs
- delete temporary files
- make sure latest net framework and microsoft visual c++ 2015 are installed