Hi product346!
I can’t see your .blend (access denied), but from your Screenshot i’d say that your Normals are not consistent.
A bevel (with one segment) is created by making a plane, perpendicular to the Normal. An Edge bevel makes it perpendicular to the Edge’s Normal. An Edge Normal is calculated as the ‘middle’ (angle-wise) of the Normals of the two adjacent Faces.
Here is what I think happened in your case:

There are three very important shortcuts, that you should use all the time:
SHIFT+N to recalculate your Normals (in Edit Mode with everything selected).
ALT+M > Merge by Distance (to remove double vertices).
And last but not least: CTRL+S to save your file!