I am making this a new thread because the Beta discussions are already getting quite lengthy and occasionally off topic.
I made a screen recording that demonstrates how the 4.9x version allowed full color icons in the notifications created by Tasker.
https://youtu.be/q2LEeuzWAx0
And another immediately after updating to 5.0b5m that shows the same task but the icon is in all white. You can see when I open the task to edit that the icon should be full color.
https://youtu.be/umb67SRnKwE
Sorry for the fast pace. If you pause on my "about device" screens, you will see that it is the same device, same ROM, and only a few minutes apart. I also open Tasker's info to show version, which should be obvious with the Material design.