Simples. Don't have any standstill or walk rest between recoveries. Slow up the 400s and make them jog 100m in 40-45s and you'll soon see the current heroes change their spots.
Your heroes are just guys with strong lactate systems who can churn out quick 400s SO LONG AS THEY GET A STANDSTILL RECOVERY AFTER EVERY ONE. Doesn't matter how short you make the recovery, they will just get better at recovering quicker. You even play into their hands even more by giving them 2 mins rest after every 4x400.
You're just making them very good at running 400s with a (short) standstill recovery. You're doing nada for their race performance (as you can see).
So take away the standstill and replace with 100m jog in 40-45s. Build to where your heroes can handle 8 x 400 at 2-mile pace with 100m jog recovery in 40s. They likely will not manage it first time out the door, so start cautious.
Doing this makes the session more aerobic in nature and better targets the energy system they will predominantly use in the 2-mile race.
As it is today you are giving your heroes the type of session they love, but does not adequately prepare them for the race. Work what they don't love by refusing to let them rest between reps. If the 400s get slower (and you must expect them to), that's perfectly okay — the race performances will get faster: which is the whole point.
Also give them another weekly session of 10k straight at ~82-85% of 10k pace. Build to 15k, but don't go faster.
You are exhausting your zeroes because they have innately poor lactate/glycolytic systems which don't respond well to hard/intense work. Give them fewer 400s but lots of walk rest in between each one. Even 5 mins. No need to do this often.
Instead of giving them lots of 400s, they would respond to (and improve better with) more tempo-type training. But not too quick: more like 90% of 10k pace for 8k. They would also like 2k reps at 10k pace with 3-4 mins rest (rest/standstill recovery for this type is okay).
Understand the difference between these two types and (as well as realizing they need different forms of training) you'll become a smarter coach. Good luck.