Cloth simulation - dent/hole on the mesh?

Hi,
I’m trying to do cloth simulation for a flag.
I made a base mesh in Maya (Subdivided a plane multiple times) and imported to UE as a skeltal mesh. I followed all the necessary process…

And somehow this strange dent/hole in the middle showed up.
I went back to Maya and checked the faces and UVs of the mesh, and they looked fine.

I’d appreciate some helps here!
Thank you :slight_smile: