what is the support limit of Udim tile on blender export ? Because i try udim on basic shapes and it's work but if mesh number and collection goes crazy it's not support export as obj or fbx for now right ?

I have no idea how the problem occurred. After finishing the model, I made first tiled uv and export not work. So i try this time create new udim and tiled it but I can't export it even though everything looks fine in the file. I tried on 2.9 daily build alpha and 2.83.2 last build. When export as obj or fbx , everytime export as single tile. you can check from file

i found out interesting stiation. I deleted udim section and voila! i can select uv island. So how should i make them udim