Probably not explaining my question very good. Maybe my gif will help show what I mean.
Are you holding Shift while clicking with the Eraser? If so you are hiding the edges instead of erasing them.
Also, as you draw out the rectangles I’m not seeing any “on red axis” tooltip. Maybe you are getting just a tiny bit askew?
In retrospect, I like Dave’s theory better. If you view hidden geometry, are there lines still there? If so and you select one, what does Entity Info say about it?
Yes, kind of. I was holding shift while clicking & holding as I dragged the eraser over the edges all at once. Then releasing the mouse. Looks like I need to review how the eraser tool works again.
No need to hold Shift if you are erasing. Shift is useful for adding to a selection with the Select tool but it doesn’t work that way with Erase.
Ok, got it now. I see how I can just select the eraser tool. Then click & hold as I drag it over all that I want to select to remove. No need for holding shift like you said. Don’t know how I got holding shift stuck in my head.
Be aware that there may also be redundant geometry in which multiple Normals can exist on the same position.
The way to fix that is select the Normal face, delete, then move onto the next. As the redundant Normals are removed, check with the Selection Tool and you will see the Normal opening up.
Occasionally, especially with small, detailed spaces or tight tolerances between Vertex Points, the model can have double-digits in redundant Normals.
Annoying, but at least easy to fix.