It seems to be a PowerBI issue due to how it stores (and sometimes loses) credentials.
The guidance I have found is to clear permissions for the Speckle data source you are using (perhaps app. sickle.systems) and re-authenticate.
- Open Power BI Desktop, when you already created visuals use the existing pbix
- go to File → Options and settings → Data source settings
Check “Data sources in current file” and “Global permissions”, mark any source that points to the new Speckle server and hit “Clear Permissions”; be aware that the source might not disappear- Close the Data source settings dialog
- Hit refresh