color calibration fails when using gnome gui on 20.10

in the past, I've used DisplayCalGUI to calibrate my displays. however, that software hasn't been updated to use Python3 properly, so it doesn't run on recent Ubuntu releases. I thought I'd try the builtin gnome calibration, but it seems completely broken on 20.10. I've tried two difference systems with fresh minimal installs, each has a different display and a different brand of colour calibration hardware. in both cases, they get to testing the coloured swatches, and fail, with an error saying:

"Calibration failed!

An internal error occurred that could not be recovered. You can remove the calibration device."

however, looking in the output from `journalctl`, colord seems to claim that it succeeded in generating a profile. So I'm guessing there's something broken in the integration between colord and gnome-settings? all I know is it reports that it failed, and gnome doesn't show any new profile to use. here's the `journalctl` output:

Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: No of test patches = 64
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Omitted 0 zero measurements
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Find white & black points
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Initial white point = 1.051779 0.999535 0.796168
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Creating matrix...
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: [46B blob data]
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Matrix = 0.615651 0.622859 0.645454
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: 0.647113 0.653246 0.680660
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: 0.531396 0.531212 0.553325
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Creating matrix and single gamma curve...
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: [26B blob data]
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Matrix = 0.009811 0.389211 0.558809
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: 0.144281 0.347751 0.505066
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: 0.198306 0.283542 0.312788
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Gamma = -1.574397
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Doing White point fine tune:
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Before fine tune, rel WP = XYZ 0.95783065 0.99709777 0.79463644, Lab 99.887672 -0.619729 2.283133
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: After fine tune, rel WP = XYZ 0.96420288 1.00000000 0.82490540, Lab 100.000000 0.000000 0.000000
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: abs WP = XYZ 1.04542265 0.99666916 0.76687003, Lab 99.871064 14.218222 4.582465
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Black point XYZ = 1.04542265 0.99666916 0.76687003, Lab = 99.871064 14.218222 4.582465
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Scaling White Point by 1.003342 to make Y = 1.0
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Display Luminance = 0.940928
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: White point XYZ = 1.048916 1.000000 0.769433
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Black point XYZ = 1.048916 1.000000 0.769433
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Done gamma/shaper and matrix creation
Dec 23 13:47:29 krait.sudo.prv colord-session[514703]: Profile done

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: colord 1.4.4-2build1
ProcVersionSignature: Ubuntu 5.8.0-33.36-generic 5.8.17
Uname: Linux 5.8.0-33-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu50.3
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: X-Cinnamon
Date: Wed Dec 23 13:51:43 2020
SourcePackage: colord
UpgradeStatus: No upgrade log present (probably fresh install)