External keyboard Logitech Slim Folio Pro not always allow me to type text on iPadOS 14.2
Restart your iPad
(or sometimes removing the keyboard, turning display on/off, and then reattaching the keyboard works, but less often)
I run into this problem frequently with the Smart Keyboard with the 1st-gen iPad Pro 11&quot;. Even though some keys are recognized—such as being able to bring up the Spotlight search with CMD+Space—none of the text keys work to be able to type anything in. Restarting is the only guaranteed workaround I've found so far.
For the quickest restart—about ~45s in total—do this in quick sequence:

Press Volume Up button
Press Volume Down button
Hold the Power Button until the iPad shuts down and the Apple logo appears