Strongbox + orb of Alchemy + Omen of Dextral Alchemy

I tend to use essence on my stuff more than Alchemy, so it piled up. I was wondering how to use it and the associated omens.

I tried to use it on strongboxes, with the suffix omens to make boxes more rewarding.

I don't know exactly the issue, but what I observed so far

1. the omen isn't consummed
2. the Alchemy seems to have the expected effect (even more maybe : I managed to get a strongbox with 6 affixes upon using an Alchemy)

I'll try more things around this to try and refine my bug report, please don't ban :D