I can't select My Apollo and any of it's inputs from the IO menu.
This issue is usually caused by one of these things:
1:You've inserted the devices into your project in a wrong order, or your Audio driver was accidentally disabled when you tried it:
Create a clean Live Set, and make sure your Apollo is turned on, and selected as the Audio Driver in Live's settings,
Then first drop the GroundControl Master device into your master track,
then a Channel device to an audio track. (This order is important. )
2: Your Max install is either outdated or damaged:
Try to install a separate Max version instead of the bundled one:
https://help.ableton.com/hc/en-us/articles/209070309-Using-a-separate-Max-for-Live-installation
Download the latest Max version, then install it.
Then In Live's settings go to Files&Folders, and browse for the Max app you just installed. 
Then you have to restart Live.
3: Something is messed up inside Console:
Sometimes if you connected a lot of Apollo interfaces over the years, and you switched them up, the ones you don't use are still visible in your prefrences, and that could cause some issues.-First open Console, and go to the settings windowAnd try to remove every Apollo device that are not currently in use:
