Switch to Light - Problem with Osram Smart+ Plug?

Hi,
I just looking for a way to turn on / off different entities in one group.
Especially I have 1x Shelly RGBW and 2x Osram Smart+ plugs which I want to combine to one group.

I tried it with this:

- platform: switch
  name: s2l_beleuchtung_vitrine1
  entity_id: switch.beleuchtung_vitrine1_on_off
- platform: switch
  name: s2l_beleuchtung_vitrine_background
  entity_id: switch.beleuchtung_vitrine_background_on_off
- platform: switch
  name: s2l_beleuchtung_vitrine2
  entity_id: switch.beleuchtung_vitrine2_on_off

And added this to my light.yaml:

- platform: group
  name: Beleuchtung Vitrine
  entities:
      - light.s2l_beleuchtung_vitrine1
      - light.s2l_beleuchtung_vitrine_background
      - light.s2l_beleuchtung_vitrine2

After a restart I can implement the entities “light.s2l_xxx” to lovelace and if I turn this entity on the switch entity also turns on.

But If I turn on the entity “Beleuchtung Vitrine” only the background turns on, the beleuchtung_vitrine1 & 2 arent turns on…

May one reason is, that the background device is a shelly and the other two are Osram smart+ plugs?

Or do I misunderstand this code?

Regards
Timo