I think the issue is that the Crafting Pylons don't calculate your score the same way as the endurance matches. With the Crafting Pylons the number of waves you beat doesn't have an affect on your score, they use the summoning multiplier.

I am sure you have noticed this while playing, but on non-endurance matches you get a multiplier for summoning large numbers of extra monsters. I dont' know what the exact formula is, but to get the highest multiplier out of summoning you need to summon one monster less than the total number of monster kills you have. This also means that you won't kill every single monster by the end of the match and you will need to attack the Crafting Pylon to end the match. If you summon the exact number of monsters you have killed then you won't get a high multiplier. I have gotten a x50ish this way after killing roughly 2000 monsters.

I don't know if the multiplier will get much higher if you go through every wave and then summon all the monsters you need on wave 1337 but I think it is worth a try. Just remember, the most important factor is for (Summoned monsters) = (Total monsters killed) -1

Max summon multiplier on epic fields is 50x

To get that multiplier you have to kill at leat 1606 monsters and as mentioned above summon 1 less monster than you have killed

also if you kill more than 2x 1606 monsters you can summon 1-2 less monsters than you have killed, if more than 3x1606 than 1-3 less and so on.

So if you killed 10 000 monsters: that is more than 6x 1606 and less than 7x 1606 so you must summon 9994 - 9999 monsters. There will be monsters left on the battle field, and you must be sure that no more monsters are killed, so switch gem to "target structures" and be sure it has the pylon in range. BTW if you summon 10000 monsters your multiplier will be 1x if 9990 a little less than 50x so don't over do it.