An "instance" is the exact IP address Octoprint is using. Usually it's 198.162,1.X with "X" being the different instance. I have 2 instances suddenly showing using OctoPrint now, each ending in 5 and 8. *
8 is an address that's newly being used now. If you're able, get the "Fing" app. Within it you'll be able to see all "instances" of your IP address being used. For example, I have about 12 set aside, it seems. Some are being used by by wireless printer, others by other wireless devices.
One thing being used is my Raspberry Pi2B+, which is now the server for the 3D printer. And for it being used, it's accessing both the 192.168.1.5 and 220.127.116.11 "instances."
Hopefully I'm describing this clearly. I'm not a professional developer, obviously.
Let me try this from a different point of view. I'll upload an .stl file in Cura. I'll slice it. And the option to "Print with Octoprint" is now an option in the bottom right hand blue "Print" button, which I assume has changed due to the installation of this plug in.
I then presents a modal saying "sending to Octoprint" nd then another, "Saving (or storing- I can't remember exactly) in OctoPrint.
And then nothing. No response by the printer. That's where I'm hitting this idle, dead-end, or something that's diverting or killing the code path from "OctoPrint" to the printer itself. This task seems to be handled by your plugin. Perhaps I'm wrong. Most likely, in fact. But I thought you'd be a good person to contact and see where you might see the problem so I can get things working again.
I sincerely appreciate your time and effort and a for providing such a fantastic plugin.