Good catch, and sorry for the wasted time chasing that! That was a real bug — the progress bar was calculating progress toward a +2 Stardust gain that could never actually happen, since a single warp is hard-capped at +1. So it kept filling past 100%, resetting, and chasing a threshold that didn't exist.
Just fixed it in Update 2 — the bar now correctly targets the one real, achievable threshold and just sits at 100% once you're ready to warp. Thanks for flagging it, this one would've been easy to miss otherwise.