95 Grand Cherokee, wont move when warm

1995 Jeep Grand Cherokee 4x4. 5.2 with automatic trans.
It will move in all gears when you first start it, but sounds like the front pump is whining?
When it gets warmer/operating temp. It wont move at all in any gear and I don't hear the whining noise . It feels like its in neutral in all gears...
Fluid is at correct level and it looks good, no burned fluid or debri that I can see in fluid.

Thoughts?

Sounds like fluid is not getting to the pump. The more you drive the debris is clogging up the filter. When you shut off it settles back into the pan. Change the filter and fluid.

Thanks for the reply, I ended up talking to few transmission places and they said the clutches would grab with the colder thicker fluid but when it was warm they wouldn't grab - so the trans would need a rebuild to fix this. I pulled the engine and scrapped the rest of the jeep.