Okay - the fact that I was logged into LibreTexts was the cause of that issue. I logged out of LibreTexts and there is not a problem on the Canvas side.
However, I notice that there are still some of the LibreText navigation bars in Canvas:
Students can click on the links and wander around LibreTexts...which isn't necessarily a bad thing - but I pretty much desire they concentrate on the class.
I have noticed that if I go into Canvas Modules (Libretext sections show up as sections of a Module) and select ANY of the Libretext sections the navigation bars are NOT present until you go to the next section.