Shield recharge drones don't work properly+combat missions trouble

[Groundwalker]

Shields: Behemoth MK-3.
Drones: 2 shield recharge drones.
Test:

I totally discharged the shields by booster and counted, how quickly they recharge. It took them 50 seconds. Discharged them again and used 1 drone/2 drones at the same time/2 drones one after another - all three times it took the same 50 seconds to recharge the shields. Sometimes the drones work, but very rare.
The game is "clear", no mods installed.

The second item is combat missions. I took 5 missions yesterday (2 - station protections, and 3 patrols) - there were no enemies in 4 of them. I was flying around, waiting and...."Mission complete. Here is your payment". No combat at all.
It would be also great if you add some Riot squads: it is too quiet otherwise.

[solntcev]

Looks like mission counted as finished if no enemies is near target zone. And spawnet ships can show up later, as they take they time to arrive in zone.

[Groundwalker]

Looks like mission counted as finished if no enemies is near target zone. And spawnet ships can show up later, as they take they time to arrive in zone.

Often they get quickly destroyed by zone defense, because there is very few of them.

[Santi]

Sell your shield recharge drones and then buy them again, that should make them work, but be aware that they have been severely nerfed and do not recharge as quick as before.

[Groundwalker]

Sell your shield recharge drones and then buy them again, that should make them work, but be aware that they have been severely nerfed and do not recharge as quick as before.

Tried all possible ways: sell-and-buy (directly and remotely), recharge in/out of combat...Nothing helped. "Behemoths MK-4" recharge in 57 seconds either with or without drones. Made around 6-7 tries. They just don't work...
Besides could anyone tell - what difference between "medium" and "hard" difficulty levels?