You know MyBB does not come with an active htaccess file. It's packaged with a htaccess.txt file which you then rename to .htaccess if needed.
I know you posted the contents of the MyBB htaccess file, but did you post the contents of the text file or an active one ?
This may be a solution, making an active htaccess file in the MyBB folder may cause the site to ignore / override the htaccess at the root.
I know you posted the contents of the MyBB htaccess file, but did you post the contents of the text file or an active one ?
This may be a solution, making an active htaccess file in the MyBB folder may cause the site to ignore / override the htaccess at the root.
What goes around comes around