I can't select some elements in the Rhino file

I can’t select some elements in the Rhino file. Some work and others don’t. I have all layers unlocked and visible, I have nothing hidden, and they are not in blocks. I discovered something strange; the only way to select them is by dragging the cursor, but not with a click. It works if I select it that way and isolate the object in question, but if I go back to work, it is not possible to select the elements.

I uninstalled Rhino, reopened it, and the problem is gone. It doesn’t happen in other files, but if I copy the content into another file, it works a couple of times and then reappears.