Change of settings is not stored.
Hi. Thanks for reporting that.
Could you please provide more detail, possibly some steps that could be used to replicate the problem.
If I change settings for navshowcategories and save the changes, I don't get a response that settings are saved and the page doesn't show a change. Other changes are stored correct at the same settings page.
You can test it at http://moodle2.de. Admin access data at starting page. This is the German public demo page.
Thanks for the report. I'm marking this as closed as this has been resolved recently by MDL-24202.