On
Debian Testing,
Libreoffice
Version: 5.4.2.2.0+
Build ID: 1:5.4.2-3
CPU threads: 4; OS: Linux 4.13; UI render: default; VCL: gtk3;
Locale: en-US (en_US.utf8); Calc: group
The usual procedure Insert → Caption is not possible as “Caption:” is missing…