loop tool does not create a circle

Question

I want to make a circle edges loop using loop tool ads on. This is my edges

And when I apply the loop tool circle this is what happened

here's my blend file

Answer 1

You do have bad geometry. To find and fix it it, I did the following in edit mode:

Go to face select mode and select most of the faces.

Then type h to hide those faces

This isn't strictly necessary but it makes it easier to follow the next bit.

Next I went into vertex select mode, and selected every vertex

and I typed m to bring up the merge menu

and I selected "by distance"

and in the lower bar it told me that it had removed vertices:

Next I tried to select the vertices that you want to make a circle using alt-LMB after deselecting all with ALT-A. But that failed because you have some extra vertices that are not near enough to each other for 'by distance' to work with the default settings so I opened the merge tool information (at the bottom left of the 3d view)

I had to set the merge distance to 0.01 to get six additional vertices.

After that I reselected the ring, and Loop tool -> circle worked fine.

follow that with ALT-h to unhide the hidden faces and that's that.