Volume Slider iOS app

The volume slider is at 100% in my app and my device via UPnP is playing at the correct volume set by device but if i touch the slider on the app it changes the volume of the device to 100%. If i go into settings and enable software volume control it doesn’t seem to make any difference.
is it possible to disable the slider or explain the correct setting, i am using the latest app and software, this happens in both app and software.

Some apps have, in addition to a slider, provide a button to allow incremental volume increases and decreases (see Volumo). Might that be added to our favorite controller?

I have the same issue - software volume control works correctly with local outputs but isn’t disabled in DLNA mode no matter what the setting of the Software Volume Control slider. This behaviour is the same from both the application running on the Mac of from the remote.