404 on all plain URLs

*crickets*

This is a strange behavior. But it works fine on all my sites. I just tested it. So there seems to be a conflict with another plugin or your theme. Please follow this checklist https://petersplugins.com/please-follow-these-simple-steps-if-you-have-any-problems-with-one-of-my-plugins/ and keep me informed. Maybe I can fix it.

Regards.
Peter

Sorry for the delay. I’ve been going through all my plugins.
When i disable WPML Multilingual CMS plugin the problem goes away, it appears to be incompatible with WPML? https://wpml.org/
I am using Language name added as a parameter (https://tealunicorn.com?lang=vi – Vietnamese)

oops I see your plugin page lists WPML compatibility. Maybe the option i am using is an exception

I’ve also tested a number of permutations to see if it is WPML+some other plugin, but can’t find anything.
I’m clearing the cache each time.