You can put in a request for a new option if you have Lifetime PLUS. Doesn't mean that it will be added to the trainer. It has to first be approved by the trainer maker and then voted on by the community before it's added to the trainer.
hold TAB and wheel will pop-up. Then just select with mouse. 🙊
Or if you are using a controller, hold the left bumper button to bring up the weapon wheel and you can select between the ammo types there.
ahh ok, thank you very much 🙂
I just tried that. Ran into the same issue. Some enemies still turn invincible.
We can only fix it with a savegame and instructions on how to easily recreate the issue every time.