I am unable to reproduce the problem as described. Try it:
git clone --single-branch -b hugo-forum-topic-49368 https://github.com/jmooring/hugo-testing hugo-forum-topic-49368
cd hugo-forum-topic-49368
hugo server
And the menu is defined identically as mine of course.
I’m using Firefox 124.0.1 on Fedora Sericea 38. But I also tried in Chromium which I have installed and it shows the same issue. So I don’t think it’s worth trying FF in safe mode. My chromium is very vanilla, only have it to run work stuff like Teams and Outlook.
I’ve published the theme here on gitlab in case anyone can tell what I’m doing wrong. It’s based on the default hugo template when you create a new theme, I just modified a few files so far.
Ok I see I read the wrong place, confused the pages with the menu. But I still can’t get it to work on my own theme. It’s here on gitlab if you want to take a look.