Normal.
If you take a look on this live statistical data then you'll see that statistical drop rate for MEF from medium security settlements hardly attain 0.5 SEED/settlement visited. And this means - I must underline, from statistical point of view - that you must visit at least 6 bases before starting to complain. (1 SEED = 3 MEFs)
Otherwise - it's an RNG thing.
Scanned 14 settlement and still nothing.
I guess Fd messed up with Mef...