Assigning PlateIDs to Polygon Shapefile

I’ve created a polygon shapefile in ArcGIS and have loaded it into GPlates to assign plateid and other information. It appears to work perfectly, but rather than getting a polygon file as a result it generates a polyline. Am I missing a step? I’ve browsed through docs and tutorials, but have yet to find a solution.

Ok, I just saw a note in a previous thread about Union of polygons with basically the statement saying if my polygon crosses multiple plateids, the result will be polylines, if totally with a plate cookie cutter polygon, it will return a polygon. I hope this feature is added in a future release. I’m envisioning a workflow where I have reconstructed paleogeographic maps and I create interpretive polygons in ArcGIS or QGIS, then reverse reconstruct the new polygon shapefile to present-day coordinates.

Yes this functionality is partially implemented, so I’d like to get this into the next release (or at the very least the following release since the next release is coming out fairly soon, in the next few months).

Then GPlates (and pyGPlates) will always output polygons (possibly with holes) instead of polylines as mentioned in the union post you found.