I think you are describing what is normal. No pump/guage combination will give a reading on a Presta valve other than on the downstroke of the pump piston.

As someone mentioned, a Presta valve is air operated...in effect it is no more than check valve, similar to the check valve at the bottom of the pump to prevent air from flowing backward from the tire to the pump on the upstroke, but the Presta valve is smaller and operates (closes) at a very small pressure differential.

Picture this. A simple schematic of the tire pressure guage pump would be pump>check valve>guage>check valve>tire. As you pump down, the check valves opens and air, at increasing pressures enter the tire; but, as you reach the bottom of the stroke, higher pressure in the tire closes both check valves...the guage is now isolated from both the tire and the pump (pressure = 0). As the down stroke begins the pressure increases on the check valve between the pump and the guage, so you will see a reading, but no air flows to the tire until the pressure in the pump/guage reaches a pressure equal to the current tire pressure and the Presta valve opens. If you could take a very slow motion film of the guage, you would actually see it come up to the same pressure as the tire and then jump slightly as the Presta valve opened.

A Schrader valve on the other hand has a pin in the chuck that pushes the valve (spring loaded check valve) down and connects the tire/guage into one unit.

Proper technique with a Presta valve/pump is to read the guage during the downstroke and pump until you see the needle reach the desired pressure (before dropping back to "0".

You might be able to find Presta specific tire guage or pump that when pushed down onto the valve would push the Presta pin down and allow a reading, but I'm pretty sure you would find it to be the same reading as seen on your last downstroke.

Does this seem logical to everyone?

Rhumb