Field Parameter not working with personal Bookmarks

I was excited to use the new Field Parameter functionality that is in preview with the May desktop release.  I created a Field Parameter using several measures in my dataset.  I then placed the field parameter field as the Y-axis on a line chart, with Year and Month in the x-axis, expanding so we see Year and Month.

After publishing the report to the Test environment in my deployment pipeline, it displays correctly.  However, when a user creates and uses a personal bookmark for the page, the Year and Month fields in the x-axis disappear:

Has anyone else noticed similar behaviour?