Questions:
Why PPTZ7300 can't dewarp when used as PPTZ?
Answer:
It's spec. If the camera is used as PPTZ (The fisheye camera monitor all angels of a location and the speed dome points toward an area on the fisheye live view), then FE live view won't support dewarping. If it is not used as PPTZ (SD camera acts as a SD camera and Fisheye camera acts as a fisheye camera), then fisheye dewarping will be available.
Reference:
RE: [ EVS - 201610286006 ] PPTZ7300 (F/W v1.01) PTZ settings greyed out; PPTZ7300-FE live view doesn’t support dewarp Quad view