Data set refresh from SQL server taking a long time

Hi,

I publish and manage several Power BI reports across multiple workspaces all pulling from the same sources (SQL server), but only two reports in a particular workspace are having this issue.  It is taking from 1 1/2 to over 12 hours to refresh these two reports if they refresh at all.  They only take a minute or so to refresh via Power BI Desktop and have only taken a few minutes to refresh in the portal in the past.

I tried to re-publish these reports from Power BI Desktop to see if that would fix the issue but did not have success.  I do not get an error but the publishing never completes.  When I cancel publishing, I see an error that the "Object reference not set to an instance of an object."  When I try to publish these reports to a different workspace, it completes without issue and I am able to refresh the reports in the different workspace within a few minutes without any issue as well.  Unfortunately, I cannot delete the existing data sets/reports and re-publish them in the existing workspace because I need the URLs for the reports to stay the same.

Here's the screenshot of the refresh history for one of the reports:

Any thoughts on what might be causing these issues and what can be done to resolve them?

Thanks,
Kevin