[GAMEPLAY] Smite cooldowns either confusing or not refreshing with poacher's knife

With some testing with Jax and Yi (typical speed clear junglers), it took notice to me that with the new 2 smite system, it would be possible to get 3 smites over a 30 second period using 2 full charges and the 50% reduction from kills by smite and Poachers Knife. This however, was not the case on some occasions. Sometime a smite would fail to refresh the cooldown. I'm not sure if it was because I had to land the kill with smite, which I did and it still happened.

I'm not too sure as to why this is, is it 50% of the current charge or 50% of the 75 seconds?

My assumption is that the smite has two internal counters, one for the global 15 seconds and one charge counter counting up. As you go below 1 charge, you get a timer with the global substituting the global counter, which doesn't seem to work with smite and poachers knife.