pdf export format changed recently

We have a report that runs daily and sends pdf export to a user. All worked fine until the last week or so. The pdf export format has changed and no longer quite matches the format in the designer (web and windows versions).

Some of the visualisations that appear separated in the designer overlap in the export.

2 visualisation that are designed to overlap to show a stacked chart in a matrix are no longer correctly aligned in export. Again, they look perfect in the designer.

Any thoughts? Is this something Microsoft have recently broken or have I just been lucky that it's worked to date.