Changed environment from air to water doesn't alter electric field

Good afternoon,

I have two electrodes set apart several microns, with their voltages set to p/m 5 V, and I'm measuring the electric field norm between the two tips. I want to see what would happen to the E-field when, instead of being surrounded by air, they are submerged in water.

I have a large cube surrounding the electrodes, with its material set to air. When I take a 4 micron high, Z-axis cut line to get the electric field between the electrodes, the 1D plot is identical whether or not the cube is material set to air or to water. I've changed the electrical conductivity of water from the COMSOL default value of 5.5E-6 S/m to 0.05 S/m, but no luck: the data is still identical, the electric field unchanged.

Any ideas on what I could be doing wrong?

Thank you all,
Cheers,
Daniel