This is basically it. Tested on debian 12.
How to reproduce:
- set package version hold, in aptitude or with apt-mark hold "packagename"
- check in synaptic that package is not marked as 'held'
- check with dpkg --get-selections, that package is set to hold
Second path:
- set any package version as 'held' in synaptic.
- check that dpkg --get-selections does not show this package state as hold
- re check that package is still set as 'held' in synaptic.
Expected behavior: package state in apt and in synaptic follow each other.
See also: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=276655