I can't be the only one who has had this in multiple vsns of ableton, currently running V11.
i use hardware synths with two motu midi routers and a behringer umc audio/midi interface.
due to certain quirks with the motu's and the vintage synths i have, i have to turn off midi track and sync in/out when i'm inputting/outputting midi to /from ableton so i don't get a midi loop and blow the clock up.
so to record midi, i enable track input in glbl settings, enable midi track, pick input interface, record my midi, edit it, then to record audio i turn off track input in glbl turn on track and sync output and pick output umc device on the track send it to the interface and on to the routers and the synth, i the n repeat that if there's more midi to input.
however more often than not the interface either doesn't show up or is still greyed out as an output device after the firs ttime. i have to toggle track/sync out off and on for it to reappear.
drives me batty to go into global settings to do the switch and then have to also toggle the track off and on when i get no sound (but sometimes it works).