1 game is made with unity
2 unity compiles or jit code into random memory only when something triggers it
3 the game wont create this code until you actually earn xp or if you view your xp or something that triggers the code to be created
4 the code created, sometimes, can be slightly different on different machines
5 the trainer is looking for signature of this code in memory
6 if the code isnt created, the trainer wont find it
7 if the code created is created differently on your maching, the trainer wont find it
8 if the code has multiple copies or the template code is still in memory, the trainer may find copies and attempt to attach to that
so there is a lot of things that can go wrong
my suggestion is to run the game, and do not try to use the XP option until your characters have actually earned some real XP while you are in a current play session, so that the code is definitely created in memory at the time. Basically whatever the option is trying to do, you need to have done it, seen it, or had the value change via a normal way in the game, to ensure the code is created and the trainer will find it.
I have no other suggestions.