the ring has to be made of all quads in blender any triangles or ngons will terminate (not complete) the ring (loop)… this is because blender uses the four “walls” of a quad as NSEW direction to know where the loop goes next…
the next possible problem might be your selecting method… while you are holding alt do you click on a vertex or edge loop? same idea for blender to know which way to go it needs to be on an edge loop to identify which direction to go… a vertex has 2 possible directions…
hope this helps…
