Just disable battery optimization for magisk manager and the "allow root" popup will appear
Which version (325, 327, 330)?
Any problems with flashing Magisk? I read that the method is a little bit different than with EMUI 9.0, and requires doing a factory reset and restoring data later.
Caution: Just in case: After the update and installation of magisk, adaway becomes unstable on my phone. It seems the "allow root" popup dont show up after adaway started. I have fixed this by autoallow root in magisk, start adaway, enable adblocking and set magisk to "ask permissions" again. After this, the popup shows correctly again. For now i have no clue why this was happen, another Honor 10 dont have this issue at all.
After this, you have to root the device again just like post 1 describes it.
Could you upload a stock recovery file? I'm at work and won't wait till the evening