As you can see in the attached image, I have used the Alt+click hotkey to loop select these three loops. I know the difference between these three loops; the one that is not select-able using the loop select method was created by joining a an entirely different cube on top (don't ask why) of another and then using the join feature. The other two were used with the Loop Cut tool.
My question is what about this situation makes this happen and can I do anything to fix it? Can I do something to this loop to make Blender recognize it as a full loop? This is obviously a thing that happens a lot over the course of creating a mesh, so if I'm able to "repair" or "create" a loop from an edge that is otherwise not recognized by Loop Select somehow that would be incredible. I know I could just get rid of the geometry and just rebuild it with fresh fills but even that would likely create some issues.
Thanks for your help!