Support — Iskra Volume Mixer
Write to hello@iskra.my. Please include your macOS version and what did not work.
The slider does not change the volume
Open System Settings → Privacy & Security → Screen & System Audio Recording and turn on Volume Mixer under “System Audio Recording Only”. Then click “Check Again” in the panel.
A recording indicator appeared in the menu bar
That is how macOS shows that Volume Mixer is receiving an app’s audio. Click “Reset All” in the panel or quit Volume Mixer.
How to quit Volume Mixer
Open the panel and choose “Quit”. Every app immediately plays normally again.