The Binding of Isaac AfterBirth+ V02.27.2017 Trainer +4 MrAntiFun

It was working fine but now when I launch it the Function keys don't work. Rebinding the keys didn't resolve it. Windows 10 just makes a chime noise when I try to press a key to activate the trainer.

There is no issue with the Dark Souls 3 trainer so I think it has to be an issue with the Isaac trainer specifically.

Fix it please!