Try both HDR settings on the Panasonic.
I don't think any PJ has Dolby Vision. So for this, I would let the Panasonic decode/tone map the Dolby Vision.
I have the Sony X700. I didn't have to change any HDR settings on the Sony. It just outputs to my JVC. So my JVC does the HDR tone mapping.
The PQ of both my NX5 (RS1000) and NZ3 look amazingly vibrant, beautiful and smooth.
How do the 2K contents look?