Default Font Changing After Publishing to the Service

My organization uses a custom theme to build reports in PowerBI Desktop but recently when we publish to the service, the font and some colors have been changing. Everything looks good in Desktop and correctly uses our theme, but when it is opened in the Service, the font changes to Segoe UI or DIN. We have had to manually update every font in each visual in the Service for it to appear correctly to our end users. A month or two ago, this wasn't an issue and everything published as it appeared in Desktop.

When I download a report from the service (incorrect font) and open it in Desktop, it will appear the right way again and shows the correct theme is selected. The same custom theme colors are also being shown in the Service, so the theme is probably there somewhere but not showing up properly. I have deleted and reinstalled PowerBI with no luck. Are there any other things I can check to see why our theme isn't publishing correctly?