ROG PHONE 2, Slow charging / fast charging not working while HDMI connected.

[cokadam]

I am using 18W charger via bottom "type-c port" while mirroring games but battery level always decreases instead increase. I have installed ampere and checked voltage and amper with and without hdmi connected.
without hdmi connected voltage around 7.0- 8.0V and 2 - 2.3A
with hdmi connected voltage goes below 5v and 600-800 mA.

[Anders_ASUS]

It doesn't charge that much slower but it takes longer for it to reach the same speed. You have to leave it in for a couple of minutes before the charging speed picks up.
Apps are not very reliable however as the current power draw of your phone will affect the result