audio subsystem not available - can't record audio

Hi guys,

I'm getting the following error message when I try to activate recording
on an audio track:

"audio subsystem not available - can't record audio"

in a window that has the header:

Rosegarden (as superuser)

This is happening with Rosegarden Version 23.06 "Flutterbye"
Build Key 13280f9033
Qt Version 5.15.9

Running under Pop!_OS 20.10 Linux with
QjackCtl Version 0.5.0
Qsynth Version 0.6.3
Using FluidSynth 2.1.3

QjackCtl and Qsynth are working and sound fine.  Qsynth's audio outputs
show up on QjackCtl's patchbay but no audio inputs to Rosegarden appear. 
All the MIDI ins and outs seem to be working fine.

The "self-recording" feature of Rosegarden used to work.  Is this a bug? 
Is there a workaround?  I used to use it to record (with perfect
synchronization) track by track, and sometimes double track, various
patches and synths.

Thanks for all you do, and in advance,

[email protected]