I've started a new character in offline mode. I've upgraded all my gear to Simple (GS 20 items) but am stuck at GS 19 overall. I cannot fit an item into the BACK slot while there are 2 items Capelet & Pack) both wanting to go into the OUTERWEAR Slot. On my previous online characters the pack has gone into the BACK slot.
I'm hoping that making the pack go into the BACK slot will fix my issue.
Further information: It turns out the the 2 affected items were reversed on the initial gear set, and making only 1 of the items caused the confusion as the new item wanted to go into a slot already filled and leave one slot empty. Making the second items corrected things as both items could now be fitte3d into their correct slots.