1 hour ago, PMDG777 said:

Hmm  I've never seen that before. Was this at a third party scenery or a default airport? Is it the same at default?

It was at the Flightbeam KMSP, which also has dynamic lighting.  I'll try to do some methodical testing with it tomorrow afternoon if I get a chance.

2 minutes ago, LRW said:

It was at the Flightbeam KMSP, which also has dynamic lighting.  I'll try to do some methodical testing with it tomorrow afternoon if I get a chance.

I've seem to remember reading about a similar problem af the FSDreamTeam forums about Dynamic Lighting only visible from certain angles. 
I don't know if it's related to what you're experiencing, but I'll post a link here if you like to read it.
LINK to thread

6 minutes ago, LRW said:

It was at the Flightbeam KMSP, which also has dynamic lighting.  I'll try to do some methodical testing with it tomorrow afternoon if I get a chance.

I'm wondering if there's a scenery layers issue where the lights are being displayed on the layer below the visible surface. Normally caused by things like Orbx Vector and the likes.

In my case i saw it on LOWS from Digital Design. Had this without ORBX Vector installed.

I didn't try on an default Airport because i barely use them, hard to do so if you get used to the quality of custom scenery 

10 hours ago, Anders Bermann said:

I've seem to remember reading about a similar problem af the FSDreamTeam forums about Dynamic Lighting only visible from certain angles. 
I don't know if it's related to what you're experiencing, but I'll post a link here if you like to read it.
LINK to thread

That's interesting.  I've made one night landing in the NGX at KLAX and I did not have the issue of disappearing landing/taxi lights.  I'll try using the default KMSP and see if the problem still exists or if it's only with the NGX and Flightbeam KMSP.  I'll also try the 747 and 777 with FB KMSP.  I'll wander over to the Flightbeam forum and see if anything is being reported there.  (when I'm finished with work)

Well, I ran a test at the Flightbeam KMSP, but first I uninstalled and reinstalled the NGX (1.20.8396).  I started the scenario on 30L, taxied down the runway, turned off on a taxiway, checked external views with all lights on and then with the landing lights and turn-off lights off, taxied back to the same gate I went to last night, checked external views multiple times, and no problems at all.  I then flew once around the patch and all was right with the world.

 

I would like to know what PMDG team thinks about those users who do not use the option "dynamic lighting". Why the team Prepar3D thought about the choice for users, and the team PMDG makes hard to use this option.

In v4 P3D default aircraft models may work when the external lights illuminating ground when dynamic lighting is disabled. Why are we deprived of such a choice?

Today experienced a new B737NGX 8900 assembly 1.20.8396. All the same. No external lights illuminating ground when dynamic lighting is disabled. Fps in the cockpit when you turn off dynamic lighting - about 50 fps, with on 5.7 fps!!! Is this normal???

2 minutes ago, Butleger said:

Fps in the cockpit when you turn off dynamic lighting - about 50 fps, with on 5.7 fps!!! Is this normal???

No, but without knowing your hardware hard to judge.

Edit: also the resolution you use and graphic settings (especially AA) can have big impact.

MB ASUS Z-97-K/USB3.1, Intel Core i5 4690K 4.3 GHz, 16 Gb RAM, GeForce ASUS STRIX-GTX960-DC2-4GD5 4Gb, 2 SSD Sumsung EVO850 500 Gb, DELL 2560x1440 monitor.

In the old version of P3D that the new v4 models from PMDG team at medium settings I was satisfied with everything. But in the new version v4 P3D when PMDG team tightly strapped the dynamic lighting, night flying became impossible because of the strong subsidence fps. Without dynamic lighting have a comfortable fps, but don't have external lights illuminating the ground.

Looking at your specs and the fact your using nearly half the resolution than me your fps with DL in the PMDG VC are way too low. On high demanding airports mine are around 20, thats enough for me.

Wild guessing but you may have your AA setting to high (for example: turn FXAA off, max. MSAA 2x)

Spoiler

 

I'll try to put MSAA 2x, but little hope... I don't understand why the default model P3D can be used with dynamic lights and without dynamic lighting, and PMDG is not???

The specs PMDG for 737NGX P3D :

Simulator: P3D v3 and v4

Hardware: A Quad Core, 3.0 GHz or faster processor, 8 GB of RAM or higher, a high-performance, DirectX 11-capable video card with at least 4 GB of on-board, dedicated VRAM.

Windows: Windows 10 64-bit (older OSes such as Windows XP may work, but we cannot guarantee compatibility or support) 

PMDG is a very sophisticated 3rd party add-on which will be a heavy load for the system, you just can't compare it to an lightweight stock aircraft.

Recommended settings give you an clue what system you need to the software running properly but this also depends on many more factors like running other software in the background, other add-ons, P3D settings and so on.

PMDG are sophisticated but not perfect otherwise they were be able to give us the option between DL on or off. What makes me hungry is that they have made wonderful job , they can do the best and at their level of dvlopment such issue should not happen. And  we forget the incredible plane they have bring on v4 cuz fps issu with lighting not even with system or important thing it's just a eye candy issue but very annoying for a hard simmer.  

Finally we have been just in one hand, one finger of the perfection dear simmers but we have to keep calm cuz until this day Lockheed and PMDG have always improve and resolve issu ..