Should be an easy fix anyway.
Just in case I can do something my end - there's no way to redirect trainer to correct process myself though?
Offline single player only is the term and description our trainers are written for.
That means, should a game have a co-op or multiplayer online portion, the trainer is not intended to be used in those game modes.
And that also means, that you don't have to set the platform client (Steam, Uplay, Origin, GOG, etc) to offline, disable your network adapter or pull the cord out of the wall. It's merely the game mode we refer to.