Guns Disappearing after relogging

Hello,

A couple months ago a glitch started when my friend and I were playing with each other in which our characters don’t keep the guns we find in each others world. This has led to us to stop playing the game because if we get any better weapons it doesn’t save them. When we play with different friends everything seems to work fine and it only happens when we play with each other. Has anyone else had this issue or know of any fixes to this glitch. This is on Steam.

Thanks for any help.