"Unknown" Attribute State when light is at 0% or off for sub buttons

[sylv3rblade]

Describe the bug
A clear and concise description of what the bug is.

Hi, I think there's a bug with the attributes for brightness when it's set for sub buttons

I have one sub button set to display the brightness of a couple of lights and they show "Unknown" when they are off

It displays correctly when the bulb is on:

Here's the setup for the sub button

When the base card is set to show the brightness attribute, it exhibits the correct behavior

To Reproduce
Steps to reproduce the behavior:

1. Add a bubble card for a light bulb
2. Add sub button that will display the brightness attribute
3. See unknown when it's off

I think it's similar to this bug previously raised: #677

Informations (please complete the following information):

• OS: OSX/IOS/Windows
• Browser/App: Chrome/Home Assistant App
• Bubble Card version: v2.5.0-beta.9
• Home Assistant version: 2025.4.2

Additional context
Add any other context about the problem here.

Thank you! 🍻

[Clooos]

Hi and thank you for the feedback! I will check that for the next release 👌

[nota3k]

I also noticed this in beta 9 with my Hue lights.

[Clooos]

Hi! And indeed "Unknown" should be hidden, but I've just fixed that.

This fix will be part of the next beta 🙂

[Clooos]

By the way, the new beta is here, everything should works as expected now 🤞

https://github.com/Clooos/Bubble-Card/releases/tag/v3.0.0-beta.3