Vaaling essences seems pointless

I've been fully specced into essences the whole league so far, and about 90% of the essences that I vaal just releases them unchanged and unfortunately I'm actually not exaggerating... I've seen 2 essences in TOTAL out of hundreds upgrade to greater essences, and ZERO greaters upgraded to the special corrupted essences. In hindsight, I would have made more currency by NOT vaaling essences, from the 100+ vaal orbs saved. At least vaal orbs are kind of cheap though.

At least in POE 1 all of the outcomes seem equal chance, and you can use atlas points to eliminate one of the undesired outcomes.

For me it feels like a 35-50% conversion rate for something other than popping them but I usually try for 2-3 per map but I will say greater essences in general have been quite rare for me. I've made a thread with some thoughts on what might be cool to juice the experience and give a good reason for more difficulty and loot that makes use of existing items structure.

I've gotten a lot of greater but no luck corrupting to a corrupted essence.

it should drop a corrupted essence that you can't use on anything so its as useless as the drops from chaos trials and corrupted strongboxes