While attempting to save a workbook as an HTML file after adding conditional formatting rules, the Save() method throws a NullReferenceException when attempting to get the background color for the conditionally formatted cell. This can be worked around by first saving (whether to file or memorystream) as Excel, then immediately saving as Html. However, the application of the conditional formatting background is inconsistent, whether the file was loaded from disk or generated by Aspose.Cells.
Attached is a SSCCE demonstrating the issue.