My moonstones disappear

So annoying as it is if I complete a mission my moonstones go away. This is what happens I had 107 moonstones and I was on the mission in presequel where you get that ai lady skipper and after I pulled skipper from the computer I went back to do another mission on the ship and killed a badass scav and got another moonstone but now I had 46 this has happened multiple times and it’s annoying since moonstones is how you upgrade your storage and ammo capacity

I’m pretty sure you opened a moonstone chest in her room.it cost 40 rocks.

There are two types of large flat Dahl loot chests - red ones and grey ones. As @GrzesPL says, one of the chests in the room where you pull the AI is a grey one, and they always cost moonstones. There’s another one in Red’n’Belly’s arena, and a few scattered elsewhere. It’s easy to miss the “Use moonstones” prompt that pops up when you put your cross-hairs over it, especially when in loot frenzy mode.

I don’t think that’s it because I had another incident where I had 74 moonstones and I died and when I came back in I had 40

Check again. You could also used moonstones when using Grinder. But I still bet on the chest.