I’ve never encountered this issue until just a couple moments ago. Earlier in the day I was having issues with team dungeons with constant glitching but I don’t know if that glitching then affected this. I was changing a fire gem into water during the exhange I used some coupons to cover the cost. When I went back into my inventory to then fuse the gems I had exchanged. They were gone. Along with the gem I hadn’t used in my inventory to fuse. So now I’m missing gems and the diamond and coupons I used to invest in them. What happened here?? Is there i way I can get them back? Since I used coupons there has to be some type of purchase history to confirm what I am saying. The only way they’d be missing was if I’d sold them but I’d never sell such high lvl gems.
Update I see someone has a similar issue. This was on AMs13