Hello everyone, I hope you're well!

I'm a new user to SolidWorks.  I previously have experience in FreeCAD (not the normal way round this goes, I know).  We're using 2015 at my employer.

I'm trying to create a circular pattern of a mirrored feature around a cylinder.  The feature previews correctly, but I get a Rebuild Error: 'Could not find face or plane' when I try to commit it.  

I can do it if I don't