I incorrectly started a thread in the General Category.

I believe I have narrowed down the issue.
Volume control and Playback position control seem to be having issues interacting.

You need to load a skin of the Now Playing screen that has both controls visible.
EDIT: The only skins I have tested also have the mute control placed on the Now Playing screen.

Have a track playing
Set volume control somewhere low.
Touch the Playback position Marker
Result = Volume has increased to 100% and the Volume control marker has not moved.

Set volume control somewhere low.
Hit the mute control. Result = no sound and if the skin provides appropriate image the Mute control shows mute is active
Touch the Playback position Marker.
Result = Volume increases to 100%, Volume marker has not moved and the Mute control still incorrectly still showing it is active though sound is on.

I have cleared App data. Deleted App. Downloaded beta again.
Issue remains.
Replay gain on or off
No DSP loaded
Foobar App on Phone
Library on remote SD card

Samsung Mega 3
Android Kitkat 4.4.4
Stock Samsung ROM - just de bloated a little
Foobar Mobile beta 1.1.5