If your inventory is full (or even if it's not and you have something in overflow), the invo will work but you wont get anything. Took me a while to figure it out myself, it'd be helpful if they added an error message.
Tried the delete cache trick, didn't work here (I didn't think it would, I have 2 PS4s and I get the same problem on both, if it was a local file issue it shouldn't affect both consoles).
Anyone know what the turnaround time on the support tickets are? I submitted one a couple days ago and haven't heard back yet, and I refuse to make a second character.
I had that issue last week, but it simply cleared itself and started working. I wish I could give you some advice as I know how annoying it is, but in my case it simply fixed itself.