For anyone out there experiencing the bug where your body does not show after summoning your corpse I think my friends and I found a trick to make it show.
Return to the spot which you died and render that exact area. Ensure a clanmate is watching the circle and the body appears.
This has been successful many times over many death + summonings in our current playthrough. Body does not show about every 5-6 times of summoning.
Not sure yet if this would work alone without a clanmate yet. I haven’t tested if dying again removes the opportunity for it to appear after rendering death area.