Solved

No training gain

What did you try to do?
Train my driver at +3 a session

What happened instead?
He was at 98 progress, I train and he goes to 1 progress and... The same stats as before. How?

Did the problem happen while using wi-fi, mobile data, or both?
Both

Did the bug happen in the app, on PC, or both?
App

What is the model of your device?
Doesn't matter

What is the operating system?
Android

What is the version number of the operating system?
Doesn't matter

Can the bug be reproduced?
Yes. Happened 3 times, first thread on it was removed in the thread raid event a week or 2 ago.

Additional comments:
Same every time

Hello

There are four different training options.
All. Driving ability. Mental. Physical. 
You should change your driver training options.
In order to achieve the desired progress you should set to Mental.
Your problem will be solved.

Best Regards

Sorry, hadn't noticed I had accidentally set to Driving ability... Sorry about that. 😅