Weird Truss Rod Nut Issue

[202dy]

Not disagreeing, but those splits look uniform.

Removing the plastic collar would give a better picture of the situation. May also give enough room to fit a thin wall socket over the nut-if it is a nut.

 

[JustForSport]

Yeah, if the hex socket was inside of the 'collar' with the slits, it would have to be very thin, so likely to split out when pushed, if it was stuck, as is the first picture.
The slits in the 'collar' are very uniform geometrically, and look like the top ridge of the locknuts posted earlier. However, there is no indication of the external hex flats visible and no clearance for a socket over it.
The hex corner remnants in the bottom of the hole are several degrees off from the slits, as prev mentioned.
I've not had a trussrod like this out, so no idea if the 'collar' with the slits is supposed to turn also, or not- looks like it may have some glue or something around it.
Two of the opposing slits are wider than the others- could be that flats were ground off a locknut like prev shown and the slits widened to accept a screwdriver to install it as a replacement for the original. Then, the inside hex 'remnants' are from an Allen wrench that was tapped to try to remove it.
Just my 2cts

 

[Rocky McD]

It looks like the rod has snapped off, like walterw said. Maybe there are inprints of the nut on the bottom of the channel. Looks too deep to even have a nut on it.
Rocky