Black Dots Not Centered on Faces

Hello, I’m new to Blender and I’m trying to learn how to make more complex meshes. I’ve been working on a model house to hone my skills but ran into a bit of a problem when editing one side of the house. I removed the original side of the house which was composed of 2 faces because I extruded it too far to one side. I selected both faces and removed them, then proceeded to select all the edges around the open rectangular structure to add a new, single face. As you can see below, the black dot isn’t centered like it normally should be, and is impossible to subdivide (which is what I’ve been trying to do).

I’ve searched this issue on Google which leads me to believe that this is a pretty common problem, though I’ve been having a hard time finding a solution which is why I figured I’d ask here. My apologies if you get this question on a daily basis. Thanks in advance for the help.

The dot being off the polygon center indicates that this polygon is a so-called “n-gon”, a face consisting of more than four vertices - which is consistent with the steps you describe to create it.

N-gons subdivide differently from polygons with three or four vertices. Whereas tris and quads get split up into four smaller polygons of the respective type, n-gons just get their border edges split into smaller fractions, as Blender assumes you want to keep this face a n-gon.

To solve this you will need to split the n-gon up into quads (or tris, for that matter) again.