I've noticed this bug since long before FAF ever came out so it may be inherent in the engine. However, if there is a simple fix that would be sweet!
Basically, while using the economy overlay, from the time you first fire overcharge on the ACU until the end of the game, it only displays the ACUs default mass/energy production and doesn't show resource use/changes if the ACU starts building again or upgrades something like Resource Allocation. Since it occurs with all ACUs and is easily repeatable on any install of FAF under a wide variety of circumstances, I won't bother with a log file or replay. It is mainly a cosmetic issue but it's always bugged me (pun intended ) since I like the using that overlay to figure out where my resource loads are at a glance. Thanks!