We’ve removed straight line as an option for DJI Fly drone since they would not display correctly in the DJI Fly interface.
Now the path mode defaults to smooth curves (DJI’s curves). We have not tested with Mavic 3 Pro specifically but it works fine with Mini 4 Pro. Please give us more details (iOS/Android, device used, DJI Fly version, firmware version of the drone, screenshots etc) so we can investigate further.
Please also share a link to a flight that fails to load so we can take a look at it: How to Share a Flight or Folder