Great modification HOWEVER does cause issues on the OnePlus 6.
I have narrowed it down to this application (most specifically Magisk module v6.0).
On OOS 9.0.1 or 9.0.2 it'll cause MMS issues. Cannot enter phone SIM settings without a force close.
Uninstalling application does not fix the issue.
Dirty flash does not fix the issue.
Clean flash will fix the issue.
I clean installed ROM. Everything worked again. Setup entire device again (reinstalling Magisk, it's modules, and apps) and bam FC phone settings for SIM. It'll reboot the modem (it'll show no connection for a few seconds before re-establishing a connection).
Clean wipe a second time. Set EVERYTHING up, Magisk, modules, apps, etc. The only thing I did not install was this Magisk module. SIM settings and all works like a champ.
Just FYI to the developer the uninstall doesn't truly uninstall for one and secondly it does cause issues.
Great app otherwise I've used it for quite some time now.
EDIT: Read from here to post 2775-2792...
https://forum.xda-developers.com/showpost.php?p=78390736&postcount=2775