Nested Slicer using field parameters not working on Power BI Service

I've created a dashboard in Power BI desktop that uses field parameters to 'group' related measures together, and I've used those parameters to create a nested vertical-list slicer that allows me to 'turn on' and 'turn off' various measures or groups of measures on the dashboard. It's a very cool feature, and it works like a charm when I'm running my dashboard locally in Power BI Desktop.

However, when I upload the dashboard to the Power BI service, the 'nesting' breaks. I can still use the slicer to select the high-level measure grouping to turn groups of measures on and off, but I cannot view or select an of the measures that make up that group. To add insult to injury, the 'carrot' that appears next to the high-level slicer option that normally indicates that the presance of sub-slicers is still visible on the Power BI service, it just doesn't work.

I've tried renaming the dashboard and re-uploading it to the server under a different name, to no avail.

Please assist.