simple deform modifier not working properly I have some problem using the simple deform modifier, for some reason it doesn't rotate on the z axis making a circle but it does the stuff in the image
Bend simple modifier rotates an axis around the specified one in the modifier.
When Z is chosen, the X axis is bent:

That why you have the result indicated in your question when all is aligned along Y.
If you want to keep things along Y, though, you can add a deformation origin object (an empty) and rotate 90 degrees it so that its X is align along Y: