UI 4.6: custom anchors breaking sizeDelta

Hello,

I am implementing a Time Remaining bar and would like to display it as a health bar.

I have the following values:

• time left

• max time (if you refill on time, you cannot go beyond this max)

• scale (obtained from RectTransform.rect.width, the healthbar's width on the display)

In order to resize the bar to the proper value, I do:

 remaining = timeLeft / maxTime * scale

my remaining time is decreased as Time.deltaTime. Finally, i set sizeDelta = new Vector2(remaining, someHeight)

and this works perfectly fine.

The problem arises when I change my anchors from, say, top center, to a custom one where my anchors are positioned on my corners. This is done to support proper resizing of UI elements across various screen resolutions.

The moment I change this, my health bar is more than twice the width and height than it was a moment ago.

I also notice that changing sizeDelta to:

 sizeDelta -= new Vector(1, 0)

the health bar now has at least almost normal height, and the width is decreasing at the rate of 1 / frame.

Can anyone explain to me what's going on here? Am I missing something regarding sizeDelta?

Thanks!