If the UI is set to tabbed/tabbed compact mode (using View > User Interface...), the "Tools" menu doesn't contain the "Line numbering..." entry.
Steps to Reproduce:
1. Go to View > User interface ...
2. Select the "Tabbed" or "Tabbed compact" view
3. Click "Apply to writer"
4. Click "Close"
5. Click "Tools"
"Line numbering..." can't be found
"Line numbering..." is either included in the toolbar or in the dropdown
User Profile Reset: No
Version: 220.127.116.11 (x64) / LibreOffice Community
Build ID: 8a45595d069ef5570103caea1b71cc9d82b2aae4
CPU threads: 8; OS: Windows 10.0 Build 19042; UI render: Skia/Vulkan; VCL: win
Locale: de-DE (de_DE); UI: en-US
Version: 18.104.22.168.alpha0+ (x64) / LibreOffice Community
Build ID: dbd4110cc36011042c98549d997daa79e8065aba
CPU threads: 4; OS: Windows 6.1 Service Pack 1 Build 7601; UI render: Skia/Raster; VCL: win
Locale: ru-RU (ru_RU); UI: ru-RU