Thanks for your response @EmT
I'm using the latest version of Affinity Designer, OS version is macOS Monterey, 12.0.1, MacBook Air M1, 16MB memory. The problem only occurs on this file and on one particular artboard. I was previously able to successfully export to PDF so I made a copy of the artboard and started deleting layers and found one that had a dotted path that appeared to be the offending party. Now things work fine but I seem to recall I had a similar problem with a dotted path causing a problem with exporting a while back.
Thanks for responding, @EmT, I'll create a new thread and reference this one if I experience the problem again.