JabRef version JabRef 5.2--2020-12-01--706865f on Windows 10

• Mandatory: I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behavior:

1. Export preferences with customized general fields from a JabRef instance.
2. Import these preferences (an example is joined to this report as text file 2020_Pref_Jabref.txt ) in a new JabRef instance.
3. The customized general fields are not imported along the other customizations.