Is this compatible with editor scripts?

[MostHated]

Hey there, I have been trying to find something to give me some easy numeric incrementation in editor scripts and it seemed like this might just do the trick, but I am having a bit of an issue. My designated callback doesn't seem to actually get called when the timer is supposedly completed.

I was trying to test it out by having the following:

        private Timer displayTimer;
        private void OnInspectorUpdate()
        {
            if (displayTimer == null || displayTimer.isCompleted) return;
            Debug.Log(string.Format("Percentage completed: {0:F4}%", displayTimer.GetRatioComplete() * 100));
            Debug.Log(string.Format("Percentage remaining: {0:F4}%", displayTimer.GetRatioRemaining() * 100));
        }

        void BeginDisplayMsg()
        {
            displayTimer = Timer.Register(2, BeginFadeOut,
                secondsElapsed => { Debug.Log($"Timer ran update callback: {secondsElapsed:F2} seconds"); },
                false, true);
        }

It seems to run through the timer as it should based on these percentage complete messages and hits 100% but then sits there continually saying its at 100% instead of setting .isComplete or calling my callback.

Percentage completed: 91.2354%
Percentage remaining: 8.7402%
Percentage completed: 98.9746%
Percentage remaining: 1.0010%
(29) Percentage completed: 100.0000%
(29) Percentage remaining: 0.0000%

Is there something I am missing in order to use this in an editor window, or is there any sort of known compatibility issue that I missed? I tried to see if there was any mention of usage in the editor, but I didn't see any.

Thanks, -MH