Good to see you’ve managed to fix it. For future reference, whenever subdiv gives you weird results check for the following :
– Multiple vertices on top of one another. Select all your verts –> alt+m –> merge by distance to see if that fixes it
– The normals on your faces. Turn on backface culling and/or select your model and shift + N / shift+ctrl+n to recalculate / flip your normals.
– Interior faces
– Check the sort order / individual settings of your modifiers
