Multi Language - 404 Page not using default language

I 'm working on a mutli language site and overall the language switch is working well with exception to 404 pages. Note- site is setup for English (/en) and French (/fr). English being the set default.

When the page not found is loaded on either language (/en or /fr) the correct locale block versions are displayed (logo, nav and footer). However, if you remove the /en or /fr from the url the page loads the french and related locale blocks instead of english and the default block locale (which contains english content).

Page not Found URLs:

Version: CMS 8.5.9
PHP: 7.4.3

Hope this makes sense and someone can assist!

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