1981013257 - "Boss drops 3 scarabs" mod from Exarch Altar doesn't work with Pandemonium Scarab

As can be seen in the screenshot, I have picked the altar mods "Final boss drops 3 glassblowers, 2 regrets and 3 essence scarabs".
All of these, with the same exact wording, work on the bosses spawned by the Pandemonium scarab except for the "Drops 3 essence scarabs" one. The same thing happens with all other scarab altars that I tried.