Unable to scan from LaserJet 100 on Ubuntu 20.04

I have freshly installed Xubuntu 20.4 and LaserJet 100 color MFP M175nw connected over LAN. On Ubuntu 18, scanning and printing worked without problems. On Ubuntu 20.4, printing works (automatically, without configuring anything) but scanning does not.

Trying to run xsane:

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Mar 1 11:28:09 frantisek xsane: io/hpmud/model.c 534: no laserjet_100_colormfp_m175nw attributes found in /usr/share/hplip/data/models/models.dat
Mar 1 11:28:09 frantisek xsane: io/hpmud/model.c 545: no laserjet_100_colormfp_m175nw attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Mar 1 11:28:15 frantisek xsane: common/utils.c 249: unable to load library libm.so: /lib/x86_64-linux-gnu/libm.so: invalid ELF header
Mar 1 11:28:15 frantisek xsane: common/utils.c 116: unable to open /var/lib/hp/hplip.state: No such file or directory
Mar 1 11:28:15 frantisek xsane: common/utils.c 166: validate_plugin_version() Failed to get Plugin version from [/var/lib/hp/hplip.state]
Mar 1 11:28:15 frantisek xsane: common/utils.c 210: Plugin version is not matching
Mar 1 11:28:15 frantisek xsane: common/utils.c 281: Invalid Library handler pLibHandler = NULL.
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Similar messages appear while running simple-scan

Note that my models.dat contains the entry for "hp_laserjet_100_colormfp_m175nw" but not "laserjet_100_colormfp_m175nw"

This is with the default hplip included with Xubuntu 20.4.

I'd like to run "hp-doctor" as suggested on this page but:

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fuxoft@frantisek:~$ hp-doctor

Command 'hp-doctor' not found, but can be installed with:

sudo apt install hplip

fuxoft@frantisek:~$ sudo apt install hplip
[sudo] password for fuxoft:
Reading package lists... Done
Building dependency tree
Reading state information... Done
hplip is already the newest version (3.20.3+dfsg0-2).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
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Trying to run "hp-check", "hpsetup" or "hp-setup" shows the same message.

I am too much of a noob to install hplip from hp.com. It fails to install with several ubuntu packages not found (e.g. libqt5) and I am unable to resolve that even after extensive googling.