In ArcGIS Pro, the polyline vertex display angle changes intermittently for an exported PDF file when the map scale is changed.

Workaround

Export the PDF file at a higher dpi (around 1200 dpi or higher) to mitigate the effects of imprecision in vector coordinates at a lower dpi, or use the ‘Rasterize layer in exported file’ option on the General tab of Layer Properties.

Steps to Reproduce