Here is all the usual stuff Pwizard mentioned for you if you need it.
Delete trainer and all files in
C:\Users\USERNAMEHERE\AppData\Local\Temp
C:\Users\USERNAMEHERE\Cheathappens\Work
C:\Users\USERNAMEHERE\AppData\Roaming\Cheat Happens\0x90
C:\ProgramData\CheatHappens
Learn how to make your own Trainer Cleaner for the above paths here.Link
Reboot PC to clear excess memory, get a fresh copy of latest trainer and
make sure trainer and/or launcher is in a folder excluded from virus scans. Empty quarantine folder if needed or set anything trainer related (paths and EXE's) to ALLOW. Disable any Live/Active/Real-Time tools which may trigger false positives in security software which may terminate the game/trainer when it's activated or options used.
C:\Users\USERNAMEHERE\Cheathappens
may need to be added to exclusions as well. Run trainer as admin, read the instructions and try again.
Anti-virus help page. Link
Have both latest .NET CORE Link (Both of the Net-Core MUST be installed x86 and x64) and FRAMEWORK Link from Microsoft.
At times, a new game may be needed to resolve failed options if the data in your save file was altered. Use on a new game, quit to main menu and load your save and try it again.
I tried what listed but none of it works. When I click on he trainer, it will pop briefly in my task manager and then instantly disappear having opened nothing. However, I also did notice that a temp file bearing the same name as the trainer will appear briefly in the Cheathappens\Work, before disappearing.
As I stated earlier I've only had this with this current version of the trainer, for this game. The other trainer I have from you guys are working fine.
What is your anti-virus and does it have a live/active/real time scanner that can be turned off?
I though I was the only one with this problem, i tried everything you suggested and still trainer only opens once and never again.