I got the newest version of OctoPrint Connection plugin from marketplace and it sees my printer, but never connects. I can click the button but nothing executes. After several failures, I tried the drag-and-drop of the older July version (http://files.fieldofview.com/cura/OctoPrintPlugin-v6.0.0-2019-07-18T12_32_22Z.curapackage). I am running Cura 4.2.1 (off appimage) running on Ubuntu 18.4.3.
Try as I might, I cannot get the 'connect' button to work. I can see my printer. I can request an API, but I cannot get it to connect. I have tried several flavors of API to include the generic, the app specific, and even one for my specific login. I have edited the RPi's yaml and put the API key directly into the octopi code... Nothing.
Flummoxed.