Kate: how to enable folding?

Please CC,

pretty stumped searching on Google for over 30 minutes....

Ubuntu 24.04 up-to-date, Kate 23.08.5

for a plain file with no extension, How to use indent for folding?

  - ▽ or ▻ symbol alongside line number is not showing,

I've tried .kateconfig file in same folder with contents:

kate: folding-markers on; folding-preview; indent-width 4;


Jay