Triplet entry problem [edited with more information]

Dorico 5.1.81.2225 (Jan 16), Windows 11 Home
I’m having a problem entering triplets in a work with a lot of flows (up to 22 now). The current flow is in 4/4 which I’m having Dorico display as C.
I double-click on the place I want to start to enter the triplets to enter note-entry mode, I hit 5 to change the note value to 8th note, I hit ; to initiate triplet mode’s automatic 3:2 status; I hit a key on my MIDI keyboard and I get a single 8th note and the triplet indication starts on the next half-beat.
Just a minute ago I had the problem with the very first notes of the piece, but I exited Dorico and restarted it and was able to enter triplets on the first two beats. The third beat is a quarter note (not triplet) so I turned off triplet mode by hitting the : key (shift-:slight_smile: as indicated in the list of keyboard shortcuts, entered the quarter note. Then I selected the 8th note and hit ; to enter triplet mode again. The 4th beat is supposed to be triplet-8ths but I get a single non-triplet 8th-note and then triplet-16th-rests for the 2nd half of beat 4 and the first half of beat 1 of the next bar.
Follow-up – if I use the mouse to enter triplet mode by clicking on the icon in the left-hand panel everything works as it’s supposed to. But I’d much rather use the keyboard shortcut and reduce my mousing.
What am I doing wrong?
Thanks for any help you can offer.

After hitting ;, are you hitting Return to confirm the popover before you play the note/chord on your MIDI keyboard?

No I have not been. I wasn’t aware that I had to do that. But I just did that and it works as expected.
Thank you for that tip!