Are BLK from WC bugged?
I got one for each of the last two maps I completed most recently. RNG is RNG.
I just did my fifth world completion, and yeah, keys are still dropping. I was lucky enough to get an almost 50/50 ratio of keys to charges (slightly more charges, but near enough). RNG unfortunately, as much as you might think “but I couldn’t get all charges without something being wrong, the odds are too low!”, doesn’t work like that. Each time you complete a map is its own roll for which you get, unaffected by the previous ones.
My condolences on your unfortunate luck.