UPDATE: Problem has been solved by the same dummy who created it - me!

So this midi keyboard used to work fine. But I kept getting this error opening up Studio One. It was insisting that a device was missing, despite everything working fine. The error was annoying, so I disconnected what I thought was the missing device and told it to stop telling me when devices are missing. Then I open up the song I've been working on and I've got an error in red - Missing Devices for all the channels that I was using my midi keyboard controller on. Turns out I somehow disconnected it by mistake.

So I go to reconnect it in options (and then from the Setup Menu), and it just won't.

I even followed an official Presonus tutorial, which just told me to do what I'd already been doing.

1. I Added the device (an acorn masterkey 61)
2. I click for it to use all midi channels
3. I select the device in the Receive From drop-down menu
4. The only option in the Send-To menu is "none," so I'm assuming I don't need that.
5. I tick the Default Instrument Input box
6. go to the menu thingy, and click "Reconnect." Studio One does nothing. "Apply" remains greyed out. My only option from here is to click "okay." It's not okay. The keyboard doesn't read. I reboot and get the same Missing Devices error.

This is extremely frustrating. Basically I've just rendered Studio One completely useless to me by pressing two buttons in a few seconds.

Does anybody know what is wrong / why the device won't read / what I can try? I'm at my wits end.

Thanks so much for any advice.

UPDATE: RESOLUTION

Turns out that the device was added the whole time - it just gave no indication that it was. I guess I assumed it would tell me that it was connected or something, plus it still wasn't working. I was tapping the keys and noticed a tiny little light going on and off in the bottom left-hand corner of the screen, in a picture of a midi input thing, so then I knew it was connected. It turns out I just had to re-select the input on the tracks themselves. I guess I assumed they would automatically work. Still not sure why it gave me the "Device Missing" error for every track, but when I told the tracks to take input from the masterkey 61 and then closed and opened the program, the error was gone. So, yay!