snap-store hangs building catalog on first run (impish)

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1944768

Impish live QA-test on (2021.10.06 ISO)
- hp 8200 elite sff (i5-2400, 8gb, nvidia quadro 600)
- dell [optiplex] 780 (c2q-q9400, 8gb, amd/ati cedar radeon hd 5000/6000/7350/8350)

on loading the Ubuntu Software I get

"Downloading firmware update metadata" and it just sits there.. I'm guessing this is the related issue; so I'm using this for a 'live' test and clicking the "Ubuntu Software" on the dock.

Sometimes it may seem that it's stuck at "Downloading firmware update metadata" but if waited long enough, it always ends up with "Downloading application ratings", at least on my side.

Though I agree that they most likely stem from the same issue underneath.

On a subsequent installed system (same daily; QA-test being the install; 2021.10.06 ISO)
- sony vaio svp112a1cw (i5-9400u, 4gb, intel haswell-ULT)

it got past the 'firmware update metadata" (and in a tiny fraction of the time the prior 'live' boxes were left) and appears to be 'paused' on "Software Catalog is being downloaded" (twice screensaver kicked in whilst waiting before I closed window)

Ubuntu Software starts without issues in today's build (20211008.1)

The bug is magically gone.

I've confirmed that the updated snap-store-desktop on the following ISO is in fact fixed.

$ bsdtar -x -f impish-desktop-amd64.iso -O \./.disk/info
Ubuntu 21.10 "Impish Indri" - Release amd64 (20211011.1)%