The cooldown of passive of manamune and Jayce's ult.

In the description, gaints 4 mana for each basic attack, spell cast, and for each time it worked, there is shadow on the item to show it's on cooldown. Jayce's ult is supposed to triger that passive each time, right? but the shadow is not shown properly when I use Jayce's ult.

In addition, plz check Jayce's other spell with that passive, it might not work in the same way described above, thanks!