Its up to you if you don't want to add a collision shape however your going to have trouble building sets if you dont put your own boxes on them. Its totally up to you. The knife you saw behaved that way because I put in a collision box in a certain area.

If you leave it to muvizu to calculate the box well your going to run into the trouble you have seen. I have always created my own objects however as I found using objects from places like the warehouse its more work to get it to work then it is to do it from scratch.
edited by urbanlamb on 26/07/2015

Its likely the way you have them configured when I open up the castle it says .obj remove the .obj and just put the name of the object and you have not added a collision box.

Since there is also no collision .. muvizu calculated a box which is why its not able to move anywhere so put a collision box in the castle. I have just finished a video and am waiting for upload to be turned on .. on the site.. if they dont turn it on next week i will just upload it directly onto youtube.

however the two problems I see is the lack of a collision box so muvizu has made one and it will always be way too large for the object making it unusable and the .obj in the name is likely affecting it and muvizu is not allowing it to have any properties

On a side note you also have a ton of flipped faces so the top half of the castle is not visible without it being double sided and this causes performance issues and you run outa ram fast as muvizu has throttled ram back .
edited by urbanlamb on 26/07/2015

That usually only happens after you've recorded some movement to an object. Assuming you haven't, do it do this with other imported objects, or just this one?