Precursor Effect not scaling Overseer Precursor mods (additional essence/shrine/strongbox)

Confirmed that the Overseer Precursor Suffix "Areas with Map Bosses Contain an Additional Essence" overlap with others like it and stack. However, 40% increased Precursor effect does not increase the total from 3 to 4 (or 5 to 7), and Remnants of Power notable (double effectiveness of Precursors) doesn't do anything to the total number.