Problems with "3 Player" synchronization

I have LMS 8.1.0 on piCoreplayer 7.00

Need help with settings to sync 3 Players.
What I want to achieve:
All 3 Players should play the same stream and volume should be independent on each player.
Player 1 + 2 (RPi) should power on/off together and play the same stream
Player 3 (Squeezeradio) should power on/off independent and play the same stream as Player 1+2

I do have no other plugins installed yet.

Config on the LMS "Player - Syncronize" Tab:

Player 1 -> Synchronize: "Player 2 + Player 3" Synchronize Power: "Power on/off with group"
Player 2 -> Synchronize: "Player 1 + Player 3" Synchronize Power: "Power on/off with group"
Player 3 -> Synchronize: "Player 1 + Player 2" Synchronize Power: "Power on/off separately"

But this does not work......
Behavior:
Player 1: Power on/off -> Player 2 on/off -- Player 3 still off --> as expected
Player 2: Power on/off -> Player 1 on/off -- Player 3 still off --> as expected
BUT
Player 3: Power on/off --> Player 1 + 2 also Power on/off --> ??

What am I doing wrong, do I need another plugin, do I need to apply the settings in a special order - or is this not possible to achieve?

Appreciate any input