A masked, bordered parent UIBlock2D with a corner radius above 0, bleeds child block content from the corners

[ZanKievit]

The screenshot shows the body of a child object with a corner radius of 0, with the purple border from the parent.
The bug also happens with the borders and shadows of children.

The inspector of the parent:

[bradybothwell]

I'm also experiencing this issue, in my case I'm using similar settings but without the border enabled and it's still occurring. Child objects always show a single pixel width border, even if scaled up withing the parent mask.