Here's what's happening to me in HD:
I want to create a gun for the new administrator of the PCs' team. And she'd probably have several. So I'm setting them up in the Multipower, and adding the Common Modifier Charges.
I select 8 Charges, which is a -1/2 Limitation. Then I check Clips, because she'd have extra ammo. 2 Clips is a +1/4 mod to the Limitation, so it moves up to -1/4.
I push it up farther, to 4 Clips, which brings the total Limitation up to 0.
She'd be serious about this stuff; she doesn't have powers herself, and knows she may have to fight the team sooner or later. So I consider 6 or 8 clips?
When I step the Clips adder up, it goes not to 8 but 16, for a +3/4 Adder, making the total value of the Limitation ...0.
At first, I didn't understand the step from 2 to 8, but after consulting the Book (6E1 369), I found where pushing into Advantage territory gives you 4x the clips at each new step. However, what HD is not doing is showing it as an Advantage. The total Limitation Value, when it becomes an Advantage, never rises above -0.
32 Charges should be +1/4, but instead shows as 0.
250 Charges should be +1, but instead shows as 0.
2000 Charges should be +1 3/4, but instead shows as 0.
I can work around this with Custom Advantage, but someone not checking the math might get filled with a false sense of security. So I thought you ought to know.