Items disappear

hey, all together

I realy like the game, but now I'm annoyed. I can't play it trough, because sometimes Items from my Inventar just disappear, when I try to put them in there right place. For example: the stained glas pieces into the big church-like window.

They just disappear, like I've somehow erased them. I don't know why, or even how this is happening. Usually the Items go back to the Inventar, if I can't use them in this place.

Does anybody has an idea what I could do?