I need a fermata placed on the last note in every choir voice and the piano, but this doesn’t seem to be possible. This is as far I can get:
I solved it. It’s because of the commas. When I delete them, the fermatas show up. I remember having a comma/fermata problem before, they don’t play well together.
That must be because they’re at the same rhythmic position, no?
They are attached at the same note, yes. I solved it by attaching the comma to the 1st note in the next bar and draging it back in Engrave Mode:
I have had that issue too, and would appreciate if this limitation were removed so we could add both items to a single note. Heaven! 
How about attaching the comma to the next “rhythmic slot” after the fermata?
I agree — I often want to put both a fermata and a “comma” on the same note. It would be great if Dorico would allow that in a future version.
You can literally nudge the caret by a 1/1024 and place the second pause in a second rhythmic position, there’s little need to implement a hard go-around to circumvent this apparent limitation…
I think that’s what I said. Since the breath mark slides to the end of the note anyway…
Yes, you are absolutely right, just reinforcing after Julian’s post.
I do not agree. Why should users have to know about this work-around? The fermata and the comma are, musically, attached to the same note, and they should be represented that way in the software. Dorico is designed to handle music “semantically” — why should this be an exception?
And eventually this situation will doubtless be fixed. But for people who want to use it now, a small adjustment is needed.