I don't fly much at night so I didn't notice this until now, but none of my aircraft (including default aircraft) have landing lights after I updated to v5.1 with the hotfix. When looking at the landing lights in spot view I see the light on but it does not light up the ground like it should anymore.

I found out it just happens at add on airports. The landing lights work fine at default airports. So I gets it's a problem with the airports.

With dynamic lights, the aircraft's lights are light effect emitters and the runway surface is a reflector--so the materials used for the airport surfaces will affect the intensity of the lighting.  As PBR has come on board and material characteristics related to lighting have rapidly evolved, right now there's wide variance in how well the light illuminates the surfaces on different airports.

One solution, if you are flying an acft with multiple banks of lights (e.g. inner/outer, fixed/retractable, wing/nose etc) is to brighten the light emitters way up in the effects files and only use one set of lights or the other if the surface reflects well, and both if it's an older non-PBR dark surface that needs some more dazzle.