DWP

After recent upgrade to Android 5.0 DWP stops working properly - instead of dialing number (after pressing DWP button configured Sim1 or Sim2) always invokes "Complete action using" system dialogue (e.g. embedded Phone or Skype etc)

Hello
Have you try to configure here?
Toolbox TAB -> Dual Sim card configuration

Yes sure!
I've setup the Dual Sim config screen (see Screenshot 1) - I've tried all "Device:" options, and all produce the same outcome except for Generic 3 which does not do anything.
So when I push test call on Sim 1 or Sim 2 the same result - see Screenshot 2.

Select Phone is the default, and then continue.

Done that!
Apologies, missed an important detail - as soon as DWP invokes embedded Phone app to complete the call, additional system query appears asking which SIM to use (see attach). This was not happening on previous 4.4.4 OS version as DWP was able to start calling from the right card immediately. Actually this behaviour makes separate buttons for different sims in DWP useless

Hello
Try different devices, if it can not work. No good way, because there is no public API.