So, this issue has been going on for a while now, pretty much since the game was launched. In short, I am not able to put two weapons into V's stash.

These weapons are Skippy and Crash.

Now, I am positive I made all the quests around both weapons and tried even to upgrade them to the max. Now that patch 2.0 is out, I was hoping this bug would be fixed but apparently it was not.

Does anyone know as of today how to fix this issue?

Thanks.

Old issue and old bug.

From your screenshot, you got a quest tag on both of them. What does it say?

Can't speak for Crash, but I know that once you progress to the point where you are supposed to bring Skippy back to Regina, you can no longer stash him on your wall.