A foot valve would be installed at the bottom of the draw pipe. If this foot valve is leaking, it will siphon water back out of the system. Or there may be a leak in the pie between the pump and the base of the draw pipe.
As for pressure, 55 lbs at the tank really should be enough. The pump may be at the edge of its design perameters and not quite strong enough to produce 30lbs at another 10' up. That is quite a deep well. Perhaps a smaller, secondary pump will help maintain usable pressure while the main pump provides water to a larger tank. This will take a fair bit of stress off the main one.