Add “slash” / to custom login URL

I am using translatepress for my multilingual site. It automatically force adds either /zh/ or /en/ to the pages.

When I try to add a path to WPS hide login (example.com/zh/login), the slashes are stripped out to show zhlogin. On the front end, this creates a 404, or on redirect from /wp-login.php creates a redirection error.

Any way to fix this?