I’m not sure what simplyprint is or how it works, but it sounds like your issue stems from a problem with your Octoprint or simplyprint settings. What is your hardware setup? Raspberry pi connected to rear usb port on the machine?
Simply print is just an additional cloud service/UI that runs on top of octoprint
Is your [raspberry pi I assume] connected to the rear usb port? Do you have the same problems when you control the printer via Octoprint terminal, or only when you use the simplyprint interface?
Does simplyprint use an Octoprint plugin for the integration? Check the plugins settings to make sure nothing looks incorrect.
Make sure that your Octoprint settings are configured correctly (2 extruders) and that firmware detection is enabled via plugin.
It’s plugged into the USB B port in the back.
How do I configure it for multiple extruders?
From Octoprint terminal, click the wrench icon at the upper right side of the screen. Look through the settings under the printer section “firmware”, “behavior”, etc. I don’t remember which menu to look under but just check out all the settings. Under the plugin menu in settings, check settings for firmware detection plugin and your simplyprint plugin.
There is no “firmware” tab
I believe members of the Facebook group ran into the same problem with the Mintion, a similar “all in one” camera/octoprint, off the shelf solution. It could pass dual extruder sliced files, but none of the control software has multi extruder in mind.