Alchemist's Genius does not affect Onslaught granted by Silver Flask

Example Setup:

Have a Silver Flask with a mageblood. All my flask effect on tree/ascendancy/flask prefix/enkindling orb works to scale the Onslaught values, as expected.

Have Spiked Concoction allocated on a cluster jewel. Press a life flask/unique flask to gain the Alchemist's Genius buff for 4 sec. Move speed / atk speed / cast speed values on character sheet do not change. (Be careful to not have any other flask that also provides these values, eg. quicksilver or cast speed suffix.)

All other flasks reflect their changed stats. Even the suffix on the silver flask works. But Onslaught from silver flask itself is not scaled by Alchemist's Genius.