didn't support MagiskSU?

[ming86]

MagiskSU didn't prompt SU request when open DeviceControl. Nexus 6P 6.0.1.

[amartinz]

SU detection works like this

1. first checks for common binary locations, as its the fastest way
2. if no binary is found, it just tries to launch a su command

if both fail, it sees it as "no root available".

Did not try Magisk yet, might give it a try in the upcoming days and push an update to the Beta channel.

Thanks for reporting that issue!