Created attachment 194777 [details]
Testcase showing filter bug.
In the attached testcase, a filter with width=100% and height=100% (in a 300px*300px container) renders with a black line on first load. The same filter with width=300px and height=300px does not render the black line.
This is likely another issue with resources on first load not getting correct sizing because they do not, or cannot, force layout of the element that their size depends on. I have a similar open clipping bug from way back.