Quicksand Hourglass - unintended interaction?

Chonomancer's Quicksand Hourglass refreshes 8s after the effect expires instead of every 12 seconds. This is relevant when extending its duration via Chrono's 20% Buff Expiry rate and Temporal Chains. This is what I recorded while testing my setup with a stopwatch.

00:00 - BUFF ACTIVATES
00:11 - BUFF EXPIRES (4s base + 7s buff extension)
00:12 - EXPECTED REFRESH
00:19 - ACTUAL REFRESH

As you can see the gap between the buff expiry and refresh is 8s as opposed to 1s that I expected based on the wording of the node.