Grim Feast skill bugged

So skill spawns shards that regen and overflow ES. Problem is that sometimes it's overflow less than x2 ES, sometimes it's more. I see no pattern, it seems random.

But more more annoying part is that shards that spawn not always give ES for some reason. I thought that shards have lifetime and when it's expire they just don't despawn, which is bug by itself. But they are despawn, and also they sometimes don't give ES overflow even if they're fresh spawn (<2 sec).

I ran into a similar bug when I was picking up the shards it wouldn't actually recover any ES. I would only give me overflow once my ES was full from ES recharge. Happened in Sulphuric Caverns when I would constantly get degen from poison ground. Also may be due to grim feast being linked to vitality?

happen to me too, what's more is that sometime it'll "respawn" the shard when i move away until it left my screen and then move back to found it respawned

I have the same problem, but I thought it was an interaction with the recoup mechanic.
It seemed that I wouldnt gain ES/ES overflow, when the ES recoup from the Heart of the Storm sorceress ascendancy was active.

But I could be wrong and its bugged altogether.