You get less loot from Asgard than you think
All of the loot shown on screen in the Minion Phase of Asgard is "possible" loot. This means that when you beat a squad, you will only get some portion of the amounts listed on the screen. And the % given varies drastically based on the minion level you are fighting, leading to some surprising amounts given by the various levels.
This video shows a few 'Possible Loot' screens in Hero Wars Web and then breaks down the amounts you should actually expect to receive based on your difficulty level.
Expected loot by level: https://docs.google.com/spreadsheets/d/19iRIe2F926axZtdzMJB9Eo7bCpVGz1VqIld5Eikf7u4/edit#gid=0
00:00 Intro and 'Possible Loot' available
02:15 Hero Wars Support response confirming this is not a bug
03:50 Overview of 'possible loot' by raid level
04:26 Percentage of Possible Loot dropped by each raid level and node type
07:11 Summary of real expected amounts by Raid level
09:28 Thanks!