I just installed the Update 9.0.2 for the Onplus 6
Usually I shut my mobile off during night and charge it.
The usual bahavior of the mobile is
switching on to charge mode ->
Bootloader unlocked warning ->
afterwards animation of charging the battery.
With the new firmware it stays at the Bootloader unlocked warning screen.
I checked already Magisk Versions 17.1, 17.2, 17.3.
Magisk Uninstall / reverse to stock boot image solved the behavior.
Dalvik Cache were cleaned.
Complete reset / format of all partition didn't solved it.
I think there is a bug with the magisk patched boot image that is causing the not switching inzo charge only mode.
Previous firmwares for Oneplus 6 had no issues with charging while being off.
Update: its an issue of the Stock Rom from oneplus.
9.0.2 freezing at bootloader warning
9.0.3 charge like expected
9.0.4 freezing at bootloader warning
And it will likely keep existing... There's nothing in Magisk v18.0 that is supposed to fix this issue. Actually, from the research that has been done, it is quite likely that there's nothing that Magisk can do about it at all. It seems like that this will be an issue as long as the kernel has been patched to force boot with ramdisk, something that isn't specific for Magisk, but quite essential.
There where reports of OxygenOS Beta 7 having fixed the issue (and beta 8 breaking it again), so the ball seems to be with OnePlus.
Hi guys, the German Android Forum was bringing to these thread...
Can't confirm that OnePlus 6t isn't charging while rooted and off
Only the charge animation you won't see because op6t is showing the yellow warning message about open bootloader.
Try it for yourself.