Try this.
1) flash zoe and choose dirty flash. dont choose to flash magisk. then choose whatever options u want.
2) after done, flash magisk 16.4 and reboot.
hey flar2 just wanna ask if u have issue with delayed notification? im on OOS 5.1 EX 3.02.. the notification for my whatsapp is delayed, i need to open the app to get the msg. just wondering if anyone of u are having this problem.