"Connected", but not really

I can't seem to figure what is going on when printer control software (MatterControl) says "Connected", but none of the controls work. Devices and Printer says RAMBo and lists a COM port. Device Manager also recognizes it. Usually, when something is wrong with the connection, it will just say "Connecting..." indefinitely. Any idea what the issue may be?

Is the printer turned on? On some boards, you can connect to them just from USB power.
If you are using a Windows computer, try ejecting the device from hardware. Unplug USB and plug back in. Also restart any host software you are using.

The printer is definitely on. I'm using a RAMBo controller (v1.2), so it can't be powered via USB like previous versions of the board. Everything is powered through an external PSU connected to the board's power input.

I'll have to try ejecting the USB device, unplugging and plugging it back in, and restarting the control software. Any other advice in the mean time would be greatly appreciated!