Thanks for the info! Actually, I think the limitation is indeed on Alexa's side, but more specifically with mixed groups containing both native Alexa-compatible covers and Shelly ones.
I have a group called "Persianas" (blinds) with several Tuya motorized blinds that work perfectly with percentage control in group mode. If I say: "Alexa, set persianas to 30%" → All of them go smoothly to 30%.
The moment I add even one Shelly 2PM Gen3/Gen4 blind to that same group, Alexa breaks percentage control for the whole group. It immediately says "I can't do that" or similar when asking for a percentage.
If I remove the Shelly blind from the group → everything goes back to normal and the Tuya ones work by percentage again without issues.
So it's not just "Alexa doesn't support percentage in groups" in general (because it does with pure Tuya), but rather that Shelly's cover implementation is not fully compatible when mixed in Alexa groups, causing the entire group to lose partial position support and fall back to only full open/close.
Individual control of the Shelly still works fine by percentage (outside the group), so it seems to be a compatibility quirk when grouping different brands/types of covers.
Has anyone managed to make mixed blinds groups work with percentage on Alexa? Or is the only solution to keep Shelly separate and use routines/scenes for simultaneous control?
Thanks! 😊