Bug with “Upgrade” feature

I can have a full set of gear to upgrade a toon, and the “Upgrade” button will not appear. I just had a toon where I completed the 6th and final piece of gear and it had the little green + , but the “Upgrade” button did not appear. On another toon, I had all 6 pieces ready to go at once, and it did not appear. I thought maybe some used diuplictive parts and I didn’t really have enough to do the full load-out, so I applied the first piece, and then the “Upgrade” icon appeared.

Not sure if this has been discussed previously