@robotfactory Not familiar with that specific Anytone.... (looks pretty slick!). I doubt that it's the problem, but try setting the time longer, so that it doesn't time out too soon.
But in reality it should work with Vox 1 and any time with you shouting in the mic.
I assume the handset is working push to talk? Is it an aftermarket handset that might have a mechanical switch on the mic?
Just some ideas!