We have identified a bug in Materialise SLM Solutions Build Processor versions 3.1 and 3.2.  

Issue: Incorrect Border Generation

The issue is that a partially incorrect exposure order of the part border is generated if there are inner and outer borders. This behavior does not occur regularly and reliably.

Because of this error, the printed parts then have lines in the areas where the layers are not 3D printed correctly because of the exposure sequence.
These results are already visible in the layer data and can be investigated with the help of a slice viewer.

You can see in the image above that sections of the outer part borders are exposed first before the inner border is exposed entirely.
The intended exposure sequence is first the inner border and then the outer border.

Next steps

A new release fixing this bug should be available in January 2021 and you will be informed as soon as it is available for download. 

In case you are impacted by this bug, you can contact our support service via this link.