Drupal views override stopped working for no reason I have a normal website, where I override the views templates for one view. When I go into the views UI, and check Other->Theme , it clearly indicates it is using the custom templates. But when I check the website, the templates are not used.

I think this happened when activating cache. (Yes, I cleared it already, and many times).

I saw that suddenly, altough the theme still worked, it got deactivated. So I reactivated it, but still the views templates are not used in frontend.

Can anyone please shed a light on this?

It is only one template file that doesn't work anymore.
I have not experienced this, but have a theory.  The default views that come with the module can be restored to their original condition so your problem may relate to the "special' nature of these views.  Try cloning the view and making your modifications to the clone.