I have a Paginated Report with two date parameters with default values. The default values function fine in Power BI Report Builder but not in Power BI Service (unless I disable preview features).
In Power BI report builder:
In Power BI Service with preview features enabled:
In Power BI Service with preview features disabled:
This appears to be the same as referenced in Solved: Paginated Reports: Default Date Parameter Broken i... - Microsoft Fabric Community, but this issue is not resolved in my end where the original poster indicated it was.