I'd posted the 44x44 size icon in previous post, if it looks exactly like that (no clipping or part of icon) then it's 44x44.
Attached is a new test .gpi with icons 68x81, it looks like this (note only the red light is present, no yellow nor green)
it has an omni directional redlight alert at intersection of N47 and N211 (point 1); here is a diagram
The alert will triggered if you are travelling south toward point 2 or travelling north toward point 4 or travelling west toward point 3.
Make sure it's the ONLY .gpi under the POI directory or testing will be wrong.