Update: So I imported the furniture mesh into Blender and did some fiddling around (checked for doubles, did a remesh etc) I exported it again (as .FBX) and imported it back into Unreal, did the collisions manually and it did the same as before, didn’t hold the items inside the furniture. Anyway, so next I imported everything into a new project and lo and behold it worked as it should in the first place. I got rid of the old project and I am continuing work in this one. Never thought this could happen.
Thank you guys for everything, turns out your suggestions were sound but the problem was elsewhere.