Can't get very basic scene to work

Hi.

I’ve got a bunch of Somfy shutters setup in HA using RFX module. These show as covers with Open, Close and Stop and I can action them using cover.close_cover etc. I’ve integrated HomeKit in HA and for whatever reason I need to use Open, Close and set to 50% (rather than Stop); not sure why the difference but it works so haven’t bothered trying to fix.

I also have some Google Home devices so have integrated Google Assistant (through HA Cloud). In this case I can Open and Close, but Stop and set to 50% don’t work. I had got around this by using IFTTT to call a WebHook for my Automations, but Google keeps forgetting about them. If I disable them re-enable in IFTTT it all starts working for a few days before stopping again.

So, I thought I’d try creating scenes for each of the actions and passing that to Google Assistant instead but I’m failing to get the scene to work.

- name: Open Ensuite Shutter
  entities:
    cover.rfy_00000c_1: open

- name: Stop Ensuite Shutter
  entities:
    cover.rfy_00000c_1: stop

- name: Close Ensuite Shutter
  entities:
    cover.rfy_00000c_1: close

I can see each of these and Open Ensuite Shutter works as expected, but the other two fail to do anything. I’ve also tried 50%, 50, shut and cover_stop etc as well as calling my automations instead of the entities directly

- name: Stop Ensuite Shutter
  entities:
    automation.stop_ensuite_shutter: On

What am I doing wrong with the command?

Thanks