Re-installing helped for 1 day, the bug is back and it is unpredictable. Only Cura2 is slicing reliably. The most successful way to slice with Cura for me is to try to start with Cura2 selected first in FS v0.8.4, then switch to Cura and try to slice it. If it works, good but most probably it won't. I found I have to repeat the process a few times, each time quitting FS and randomly playing with the engine choices, after a while, Cura works but will behave the same after the next "import". By the way Slic3r engine is also acting up, most of the time does not work but on occasion, it slices ok.
@proclaim: one thing I noticed, the imported structure is sliced in Cura but placed just outside of the platform after slicing. Slicing is shifting the object location. So there is an issue with the coordinates, 0,0 is somehow is shifted during slicing process.( OSX 10.10.5, Macbook Pro)