Night1505: I know this is GoG and therefore PC gaming, and I am playing on console, but I figure more info is always better...
Okay, searched around a bit and still can't find a fix or a real answer, but here's more info that might help someone or maybe (if I'm very lucky) get me pointed in a clearer direction.
I have a purple Overwatch. After reloading many different saves (Xbox Series S), I have figured out that when my Crafting level went from 15 to 16, the Overwatch stopped appearing on my Upgrade menu. I have not maxed it out, and I am still able to craft the Legendary version of it (so the game still recognizes that it's in my inventory), but I have spontaneously lost the ability to Upgrade it at all.
To clarify further, I am not being "blocked" due to level or materials (as with other items that show up on the Upgrade screen, but are blocked from Upgrading due to level or materials requirements), the gun just simply does not show. I also did not upgrade the weapon between my Crafting skill being at 15 and it then going to 16. One save my Crafting skill is at 15, and the gun shows on my Upgrade menu. The other save (5 minutes later, presumably after dismantling a bunch of stuff and getting Crafting skill XP from doing so), the gun is no longer showing on the Upgrade screen at all.
Has anyone nailed down a cause or fix for this?
Seconding this on PC: it's not that it's blocked from having hit the max level or max quality.
Overwatch simply doesn't appear in the crafting upgrade menu whatsoever. Every other gun appears, but Overwatch doesn't, preventing further upgrades.