The approach end of 4L, aircraft wheels sink a little into the runway, runway lights are gone and directional signs are half way in the ground. As I move forward down 4L, wheels, lights and signs are back on surface and visible. I decided to taxi on the grass next to the runway and taxiway - no issu...

Hello
while taxiing on Bravo, the parallel taxiway to runway 9/27, the red runway hold short in-ground lights disappear as I approach them. this happens the whole length. I don't notice it anywhere else on the airport, just Bravo taxiway. Thoughts, ideas??