Yes that's the cause. Removing the jewellery box frob-blocker entity causes the wardrobe to keep functioning. However that means i can frob the jewellery box before picking it. I tried separating the wardrobe frob-blocker into two parts to see if it was the touching that was causing it but that didnt help.
The box has a target on it for the control but the wardrobe doesn't. I'm afraid i'm not sure what to try next.
BTW I'd like to thank you Springheel for your video tutorials. After giving up mapping a few years ago because i just didn't have time to read and learn, I've restarted with renewed vigor due to yourself and some others within the Darkmod community. Video tuts are so easy to watch and learn - i'd like to share some screenshots for you but not sure how to attach to this post.