[BUG] Adept and Conjurer glyph damage increase is borked to less than 1/4

I’ve been playing around trying to make my fire sorc less garbage :), and i’ve noticed a strange thing with Adept paragon glyph (Mastery skills gain X% increased damage).

Currently it says 87.1% damage increase on the glyph when i put it in a socket.

Without the glyph Firewall tooltip declares 86654 damage, but when i slot the glyph in, the tooltip says 100778 damage. I don’t even need a calculator to see that the math is wrong and it should have amounted to 162130 damage. Instead it is a puny 16.3% increase, not 87.1%!

Same thing with Blizzard, where it shows just 20,7% increase.

Even more perplexing, the damage increase is not even consistent between spells. I mean, regardless of any internal formula being additive, multiplicative or whatever, arithmetic rules don’t work like that. When i switch two-hand weapons between one having “+X% Mastery skill damage” and the other that doesn’t, the spells’ tooltips correctly reflect the change in numbers. All this in town, so there’re no active effects of any kind. Checking the actual damage numbers on dummies corroborates this too!

Am i calculating it horribly wrong? I can see that some people have complained about Adept in the past but nothing that bad! I mean if the glyph adds less than 1/4 of what it’s supposed to add (and inconsistent at that), it is almost game-breaking for us pyromancers who are already at the bottom as it is.

Actually, it’s even worse with Conjurer glyph! It’s supposed to increase Hydra damage by 145.2% (x1.5 times), but in fact the tooltip on the spell indicates 24% increase, less than 1/6th! Are you serious?