I seem to have this problem too (with Publisher 1.10.1). It occurs when either of the following presets are selected: PDF (digital - small size), PDF (digital - high quality), PDF (for export) or PDF (flatten). The other presets seem to work. The document is a simple job application using Gill Sans (included with macOS Mojave) and one embedded vector image.
Problem: The export dialogue gets stuck "Calculating…" and if I click the "Export" button anyway I get "An error occurred while exporting to: …".
MacOS 10.14.6; Macmini8,1; Intel Core i7; 3,2 GHz; Total Number of Cores: 6; Memory: 64 GB.