This older thread has some suggestions that may be useful to fix the Fritzing output (they will have been using 0.9.3b, but I think the same should still apply to 0.9.9)
This was found by a search for “ground fill” in the forum search bar because I remembered this discussion. There have been a number of discussions on ground fill over the years (and most of the old experts no longer post here!) I have never used it (I rarely make boards) and so don’t know much about it other than it has issues.
Peter