FSX and impressive stock lightning

Stumbled onto this fact;

For whatever reason, in FSX stock settings (NO WEATHER ADDONS), IF YOU CHECK

'Detailed clouds" YOU WILL NOT SEE SPECTACULAR LIGHTNING.

If you choose "Simple clouds"  ... you will

Made no sense to me but I did read that if you use REX, you MUST have Detail clouds checked, so I can only quess that when checked, FSX is looking for something else or specific and when it can not find it (ie REX or whatever), you lose the spectacular lightning, 

So, now that I have found this, I will tweak my advanced all station weather settings for clouds to see if I can increase them and of course retain spectacular lightning