Oh the development version … Also tried that (JabRef 6.0-alpha2.112–2025-05-18–c06f141). It’s the same as latest release - no refs section is inserted. Even if I just open a blank document, connect and insert a ref it’s the same - no refs section. Libreoffice version info:
Version: 7.4.7.2 / LibreOffice Community
Build ID: 40(Build:2)
CPU threads: 12; OS: Linux 6.1; UI render: default; VCL: gtk3
Locale: en-AU (en_US.UTF-8); UI: en-US
Debian package version: 4:7.4.7-1+deb12u8
Calc: threaded