Yeah those seem harder and harder to get now. Out of 100 missions I looked at yesterday across about 10 systems that i'm allied with. I was able to get 1 normal mission with 5 as the reward.
UGH! That is horrible!
There is no reason to stick around a borked station or system if it stops delivering the missions you want.
Check out the system named "PIRA" near Cubeo in Imperial Space. Either Kraft Depot or Kuo Port. Both have an endless supply as far as I can tell. Been getting as many as I need for months from Pira, and several other systems in the same sector.
They are very common rewards from their Planetary Scan, Pirate Lord, Black Box/Space Salvage and Boom Time Delivery Missions. (5) per mission if you take the highest paying versions.
I just turned in 4 of these missions a few minute ago. I believe you can stack as many as 15 at a time if you want. My MEF stock is once again about to hit the cap again.