Decimal tabs in LibreOffice Writer don't seem to work. Is this a glitch?

I am trying to use a decimal tab at 5.75" in a LO Writer document. The page format is landscape with 2 columns, 0.5" margins, 1.0" spacing between the columns. The other tabs I am using are 0.25" (Left), 2.25" (L), 4.5" (R), 7.75" (L) and 10.0" (R).

On most lines the tab at 5.75" is a standard left tab, but for a small group of lines, I would like to align Roman numerals using the decimal tab selection. For those lines, I have removed the left tab and inserted the decimal tab. The decimal tab will not work properly. It behaves just like a left tab.

Is this a glitch, or is there some special way to use the decimal tab selection, one that doesn’t seem obvious to me right now? Thanks for any help you can provide!

Worked for me (but not with those settings. Make sure that you use the correct separator. In the Netherlands, the comma (,) is the official separator, and the decimal tab aligns numbers with the , correctly. When I replace the commas by dots (.), the tabs work like left tabs.