Unity Probuilderize quarters Object

Hello,
I’m making a unity 3d Game with URP. I wanted to convert the shown mesh to a Probuildermesh. Unfortunately the Mesh gets split in 4 pieces. Does someone know, how this happens?
LG

Hi @MaeschDEV, could you please share the mesh asset that you’re trying to ProBuilderize? I’d take a look and get back to you.