Scanning not working with non-default settings

I am running Kubuntu 20.04 with Ubuntu Studio on an HP zbook 15 G3. My printer / scanner is an HP Envy 5542.

Scanning at the defaults, text 150 dpi / image 300 dpi works 'out of the box'.

Changing resolution to 600 / 1200 dpi sets the scanner working (shows "Scanning..." in the display, making noises and moving the scanning parts), but fails.

simple-scan gives the error message "Failed to scan. Unable to start scan".
skanlite fails with "Invalid argument".

On my previous system, Ubuntu Studio (xubuntu) 18.04, all available resolutions worked with the same printer, so I'm sure the scanner supports the tested resolutions.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: plasma-desktop 4:5.18.5-0ubuntu0.1
ProcVersionSignature: Ubuntu 5.4.0-66.74-lowlatency 5.4.86
Uname: Linux 5.4.0-66-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Sat Mar 20 11:40:45 2021
InstallationDate: Installed on 2021-02-07 (40 days ago)
InstallationMedia: Kubuntu 20.04.2 LTS "Focal Fossa" - Release amd64 (20210204)
SourcePackage: plasma-desktop
UpgradeStatus: No upgrade log present (probably fresh install)