Polylang causing changes not to be reflected on front end

I have a WordPress MultiUser site and I was using Polylang on one of the sites.

At first it worked fine.

Then problems started happening. I thought it might be an issue that would be resolved over time. I didn’t need the translations immediately so I disabled the plugin. I don’t even properly remember the original problem I was having, it was something to do with blog posts not being editable.

I thought I would enable the plugin today and see if the issues were resolved.

Weirdly, I enabled the plugin and I added the language switched to the menu. No sign of it on the front-end.

I added a custom link to the menu. No sign on front end.

I cleared every cache I could think of or find. No sign.

I disabled Polylang.

Menu items appeared on front end.

Anyone know what on earth is going on?

Should I just give up on using Polylang and find another solution?

The page I need help with: [log in to see the link]