Redirect Doesn’t work on a specific subdomain

Hey,
I have a wordpress website in a non-english language, and it has an english section under https://domain.com/en

For some reason I can only redirect url’s that are not under that subdomain. I’ve been testing some variations and it has repeated itself with every url. (/en/title not working, other formats of url working). Important to note that /en/ is the only subdomain that actually exists on my website.

Do you have any idea what may be the cause of that?

Thanks