Some objects disappear in a certain distance or with certain angle.

[DerrickFan]

https://youtu.be/Tb3SarGgVxI

I added some objects into the game by using ImgEd, Map Editor and CollEditor. Some other game objects started to behave like this. (Not the added ones, the new objects work fine)
After I deleted the new objects by deleting the related lines in IPL file, the above situation returned to normal. I am quite sure the IPL, col, txd and IDE files are correctly edited.

Is there reasons that may lead to this situation and how I can solve it? Thanks.

P.S. Actually I just added some billboards which were not created by myself. These dff and TXD file are just original billboards duplicated from the original game IMG.

[DerrickFan]

I discovered that all these disappearing objects are from props.IPL after investigating the Map from MEd. I am wondering if I can do something regarding the gta3.dat or the IDE files. I will update this post once I figure out the solution.