Hi Richard,
I don't work with CAD data, but looked in our Support database and didn't find a bug describing this behavior. It may be and it hasn't been logged yet...
I did read through some cases and technical articles that talk about the Entity field being defined as circle.
For you and others on this thread, did the points you're working with in Pro originate from CAD; i.e. imported into Pro from dwg or another CAD format and you're now exporting again? Check that Entity field if present.
I can ping somebody on our CAD team, but we may need additional details to troubleshoot. If you feel this is a bug, the best thing to do is to contact Technical Support. I'll let you know if I hear back from our dev team on this.