Hi,
I wanted to verify whether I can sacrifice an artifact that was currently in the update mode. How much surprised I was when it happened. So I sacrificed 4 artifacts to update 5th and that 5th with other 3 artifacts I used to update another one (all same 'common' level). Eventually that caused a loss of 4 artifacts that were used in the initial sacrifice. Not sure if it's a bug or intentional behavior.
Anyone had the same?

Happened to me too a long time ago. Any upgrading artifacts keeps its level while upgrading (a common upgrading to uncommon is still a common until the upgrade is finished) and can be sacrificed with other artifacts of the same level.