Empowered Map Boss Item Drop - zero items drop

Now 4x maps in a row (different maps in different areas, T15) with 3x rare precursors (abyss+precursor+overseer), one of which upgrades bosses to empowered ones.
Clearly they are empowered with HP and damage increase and after each boss (sometimes multiple) deaths no items, gold or anything drops.
Only happens on empowered bosses with precursor tablets.
No issues before this.