Incorrect GCODE generated at Layer 4-5

[clough42]

I'm trying to print a two-color vase on my dual extrusion printer, but Simpify3D seems to be generating incorrect GCODE at layer 4-5.

Here's layer 3-4:

Layer 3-4

And here's what should be the next layer:

Layer 5-6

But this is being placed in between, at the same Z height:

Layer 4-5

This creates a web of material outside the model and squishes extra plastic into the same space as plastic extruded by the other nozzle (circled in red).

Any idea what might be going on here? Is this just a defect in the slicer?

Here's the factory file: https://www.dropbox.com/s/pileub5ak2rgk ... ctory?dl=0

The original model is here: http://www.thingiverse.com/thing:28202

[CompoundCarl]

Usually this means there's part of the model that the software doesn't like, and right now, one of your layers perfectly coincides with that problem area. So if you slightly adjust the position of these layers, you can frequently just avoid the problem altogether.

For example, if you just change your first layer height to 99% instead of 100%, it slices fine