PS4 user here, I acquired River's revolver Crash after completing his questline. But after trying to upgrade it to my level a few times, it suddenly disappears completely from my Upgrades menu and I can't upgrade it any further, no matter how many times I level up. Also can you please remove quest item tags for weapons like Skippy and Amnesty so we can craft them to Legendary, since there is in fact a Legendary crafting tab for the Amnesty. I sincerely wish to enjoy the detail of the gunplay in this game but due to these bugs, my freedom feels limited.

I'm on a PC, so I don't know how helpful this'll be, but I don't think Skippy had a legendary crafting recipe and Amnesty is bugged (you can get the rare from Cassidy, along with the legendary recipe, but the game won't let you upgrade it). I didn't see the plot-item exclamation mark icon on either Amnesty or Crash this playthrough (although I remember Crash used to be bugged in 1.3: it was non-plot when rare, but if you upgraded to legendary, it turned into a plot item and you couldn't put it up on the wall).

As for Crash vanishing from your upgrade menu: if you're below level 50 -- that's weird.

If you are 50 -- once the items hit max level, they vanish from the upgrade list (as they are maxed out and cannot be upgraded any more).

Im on PC patch 1.6 and Crash did the same thing to me around level 30. It no longer appears in my Upgrades Tab.