Ok, so I did more testing and can confirm it's not the save. I also had another save for the Sunburn trophy and I believe that this is what interfered with the trophy popping up. The minute I took that save off my PS4, Gobble's save worked without a problem. This is just a speculation on my part but the sunburn save came with a SCEmemory file and this was probably flagged as having completed the mission already or doing something prior which canceled it.
In any case, if you have the same issue I had, just restore your original save set and add Gobble's save file (resigned) and everything should work normally.
Thank you again for saving me all that time replaying the game from scratch, with your save. Much appreciated.