RESOLVED:
I went into the Server Settings on the Host computer and disabled “Use hardware encoding” and this fixed my issue. I am now able to use full screen and have the remote computer change its resolution and get a working display on the client computer.
Initially, I also disabled “Use acceleration for display processing” at the same time, thinking that this was another Hardware Acceleration issue like I was having in the last paragraph above. When I got a working display, I went back and re-enabled the Acceleration option and I am still getting a working display on the client computer. It seems the hardware encoding was my issue.
I do need to disable HDR to not have a washed out image, but that’s easily remedied.
Hopefully if anyone is having a similar issue to me, this can be a troubleshooting step they can take to try and fix the issue.
Cheers!