Just bought a MiBox (MDZ-16-AB) with an external keyboard (Logitech K400+) and updated to Oreo.
The keyboard works fine with English but i can't type any Greek characters with it.
On Settings > Keyboard > Manage keyboards > Gboard is selected but there is no option for Greek Input/Keyboard, nore a "download more keyboards/languages" button.
I installed SwiftKey keyboard, which allows me to type Greek characters with the virtual on-screen keyboard, but the external keyboard can only type in English.
I tried different combinations to change language (eg. Shift+Alt, Ctrl+space, AltGr+space), but i can still type only in English.
Any idea on how i can type Greek with my external keyboard on MiBbox3?
Did you try to turn off Gboard completely and just have your Swiftkey keyboard on the on? And/or is your mi box language in Greek? If not, try selecting that.