This game was updated on the 25th of March, likely rendering the trainer partially or completely broken. You’ll need to vote for a trainer update via the WeMod desktop app.
The devs seem to like releasing seasonal patches, which means the trainer will probably need occasional updating, unfortunately.
This should explain how to request an update: https://support.wemod.com/article/43-how-do-i-request-an-update-for-games
UPDATE:
For now, please use this newly-made trainer by STiNGERR: Gold Rush: The Game Cheats and Trainer for Steam