Hi there,
So I find your unable to edit a 360 HDR image in projection view?
1: HDR merge 6 bracketed images from Theta 360 cam.
2: Apply, and return to pixel persona.
3: Go into equirectangular projection mode.
4: Rotate around, and edit something using the inpainting brush.
5: Press ctrl + cmd + p to return the ability to rotate.
6: The moment you rotate, a ugly plane appears in the scene, that is sized and aligned to the size and position the view was in at the point of editing in step 4.
Note: Merging the 360 HDR, and saving out to disk as an HDR, then reimporting as a single file does not change this behaviour.
See attached sample screenshot.