Why wont the first letter capitalise?

I want libreoffice to capitalise the first letter of every sentence. the answer i would give would be to go to tools/autocorrect/options and check the ‘capitalise first letter of every sentence’ box but this isn’t working. does anyone know why?

This is the correct procedure. Please edit (don’t answer) your question for OS and LO version.

I have the same problem. I am using Win 10

Check if this apply to your problem:

Bug 100778 - “Start with caps” autocorrect doesn’t work if word contains apostrophe and “Single quotes” option is on

There are problem also if the previous sentence ended with a number. I think there is a bug report for that too, but I cannot find it right now.