This isn’t actually a bug

Hammer time’s 3 parts work like a combo but the ability to use hammer time is a buff

So if you use part one of the combo then wait 20 seconds you’ll break the combo but still have 9 seconds on your he ability to use hammer time so it’ll just return to the start of the combo

It’s the same as if aetherhue’s 1/2 drop off while under subtractive palette, it’ll just return to blizzard in cyan