This morning, I unloaded something from my car and closed the back hatch... no big deal. I went to back out of the parking spot and the car started beeping when moving. I stop, the beeping stops. I pull forward back into the spot, car beeps again.

I removed the back panel and got the back door open but then it never engaged. The beeping persisted and the back door still won't open now once I closed it.

Has anyone else seen this or had this issue? I read about it in another forum but never a conclusion to what the issue was.

Sounds like a bad position sensor switch. Or something jammed in it. This is the part, I believe:
https://www.nissanpartsdeal.com/parts/n ... 002,25360Q