It is every D8, yes. And it causes problems for both Chitubox and Lychee slicers.
Exporting a D8 and then immediately, before anything else, dragging it into Netfabb displays the following:
Once I run the fix on it, it's perfectly fine. But it appears that the mesh is being exported with a hole in it somewhere and it can cause the slicing process to remove two whole faces and just leave a flat vertical surface there (Lychee isn't cooperating right now I can't screenshot it :( ) if it's sliced without being run through Netfabb first.