Merge cells isn't working

Line is empty yet cannot merge cells

Hello - you have a problem and are looking for help. That’s what this site is about, but please understand no one willing to help is able to provide a sound answer without some information about your environment. Thus please provide:

  • Operating System (Windows, Linux, macOS) and its version?
  • LibreOffice version?
  • Did you already try to reset your user profile?
  • Did you try to start LibreOffice in Safe Mode?

PS I got no issue merging cells (even whole lines) into one cell using on openSUSE Leap 15.2 LibreOffice:

Version: / LibreOffice Community
Build ID: fe0b08f4af1bacafe4c7ecc87ce55bb426164676
CPU threads: 8; OS: Linux 5.3; UI render: default; VCL: kf5
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded