Hey @armin,
Thanks for pointing this out. This does seem to be a new bug that we should address. You are right that even though the stroke is set to transparent that the fill color or pattern should still be drawn. We will prioritize this with our other features and bug fixes. This should be relatively straightforward to fix, though.
In the mean time, the workaround is to set the stroke to something non-transparent, as @DaveR mentions.
Sorry for the inconvenience,
Adam