Knife tool issue

I am trying to use the knife tool to create a new topology for a model As you see in the first picture, the knife tool is suppose to create 3 edges and 2 vertexs.

However, in the later picture, you can see that blender only created two edges.

How can I fix this? Even by selecting a turret vertex and trying to join it (J) to the newly created vertex did not work. The only thing that seems to work is selecting the two vertexs and creating a line (F) between them. However, this does not join them or create a face, therefore is useless. Any help would be appreciated.

It appears that the turret mesh is not physically connected to the rest of the mesh that you are trying to cut. If so you are not getting that cut because there is nothing to cut.

Depending on what you actually want to do you could just delete the horizontal face that is not being cut by the knife and just connect across with new faces (F)

The original model came in multiple parts so I joined the two turrets with the hull. I thought that this would attach them since the distance between them should be 0 or very small. How would I physically attach the turret to the hull in order to have the knife tool work properly. There are multiple pieces that need to be “attached” to other parts, so this would be ideal.


Also if that is the case, then why does a similar thing happen away from the turret (see below)

Those faces are already connected therefore should be able to be cut. Am I missing something?

Physically look at your mesh, check there is a continuous mesh (no double vertices etc). Notice the area highlighted doesn’t look correct

Post a link to your blend file so we can see what you see rather than having to use guesswork.