Vehicle will not Move when transmission is shifted into reverse

There are a couple of possible causes with this, so we need to start with the basics.

First you said the fluid was full, but we need to make sure we are checking the fluid correctly.

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

If the fluid is correct then we need to check the pressure in the unit, specifically in reverse.

Please see the info below on how to do this. This will point us to a pressure issue or even a servo issue. So let us know what you find with this.

Let me know if you have questions about this and we can go from there.

Thanks