So its been just a little over 10 years since the original default_mp.xex modifications to enable modded lobbies was released to the public.
https://www.se7ensins.com/forums/threads/release-call-of-duty-modern-warfare-2-default_mp-xex-patcher.118219/
Wanted to make a post and see who is still...
A fix has been provided for that, you can find it at the switchroot website you are going to want to boot into TWRP and flash the zip file from the website. https://download.switchroot.org/android/extras/