Whilst doing some tests I discovered that in order for an imported step file to be meshed properly you should export it from Alibre in your preferred units (inches or mm usually) and re-import the Alibre version of the step file. This, I think, harks back to an old issue with Alibre which insisted on using cm units internally and in the API-based step file output which we used as input to the mesher. Alas the mesher used mm units by default and the resulting mesh would be the wrong size. Rather than change the source code of the mesher we used a units fiddle factor in the mesher input file. Now perhaps that bug/feature has changed in the API and we need to revisit the source code. Meantime use the above-described hack which works. The default mesh size is simply the bounding box of the model divided by 3 so if it looks like 0.3 when it should be 300 then you will be unsuccessful in meshing and you need to do the hack. This hack is not for native Alibre files, just for imported step files!