Deathwing was blinded (but not silenced) by a Dehaka using Isolation on him.
That still isn’t fixed? But yes, if it isn’t, it’s a bug due to recent changes to the status of Blinds (Unstoppable now prevents them from being applied).
Patch notes from 2020-01-22 say:
Fixed an issue where Deathwing could be affected by Blinds.
Honestly? I don’t think they really applied Unstoppable status to DW. They’re just manually listing all the things that effect or don’t effect him into the client code, and they forgot Isolation.
Isolation has two effects, it removes a players vision and Silences. Deathwing is immune to Silence, but Unstoppable currently does not remove effects that take away vision from a player.
Even Johanna and her Iron Skin can be hit by Isolation causing her to lose vision, but she can still cast abilities, which is the same interaction I am seeing on Deathwing.
OP’s post makes it sound like he was blinded though rather than losing vision. But far as I know that interaction either no longer exists or it never existed.
I have a distant memory that Contagion made it also blind (instead of just losing vision) but after looking at patch notes that doesn’t seem to be the case.
To my knowledge only Deckard has a heroic upgrade that also blinds at 20 (Respec the Elderly, storm talent) but not baseline.
DW is not immune to vision loss, of course. Just Blinds (which make AA’s not hit).
Blind and Reduced Vision are two separate effects, don’t mix them up. Dehaka has the second one which does not make auto attacks miss.
I also remembered Dehaka could talent Isolation into an additional Blind late game but he can’t. All the upgrade does is spread Isolation to nearby enemies (reducing their vision but not Blinding them)