It is possible that the drawer part of the slide, and the cabinet part
of the slide have not been fully engaged. When you reconnect the drawer
part to the cabinet part you need to make sure that the drawer part has
been pushed in all the way. It could be that the relative "in/out"
locations of the drawer part and the cabinet part are such that even
when the drawer is closed the drawer part is not all the way in. So you
may have to move the cabinet part closer to the front of the cabinet
(or the drawer part closer to the back of the drawer).

I assume that the slides operated ok before they were installed?

Measure the clearance between the drawer and the cabinet. It should be
exactly 1/2 inch.

Try a drop of oil here and there along the slide.

The position of the whole slide assembly, relative to the drawer is not
important. As long as the moving part and the stationary part are all
in a line.

Mitch