I have a VT pro in my hands and I am trying to 'run it through its paces' before hooking up the transmitter to a tank (that I don't have).

So I have read the manual, and have the unit running in 'demo' mode.

Trail 1
I set the tank pressure to 3000psi and start the 'sequence'.
After 8 minutes at the 'surface' my 'tank pressure' disappears and the unit returns to 'real surface time' (leaves demo mode).

Trail 2
I set the tank pressure to 3000psi and start the 'sequence'.
This time I immediately 'dive' to 40 ft and do nothing else.
@40 ft, 48 min 'dive time remaining', The Air bar graph reads 40 min+. The pressure ticks down as I would expect. After 8 minutes my 'tank pressure' disappears and now shows 2 hours 8 min 'dive time remaining', I can cycle through view modes but there is no Gas/Air showing anywhere - no bar graph, nitrogen/deco graph reads 2/7 - I terminate demo mode at '2 hours remaining'.

This happens time and again often loosing the readings as soon as I start the decent.

The battery reads 100%

Anyone with this unit that has any idea why I keep loosing my air reading? Or is this a service issue?