Please see example code here:
Tested on Aspose.Words 15.6.0.
When viewing the doc-file, column 1 in row 2 + 3 appears fine. But when viewing the html/pdf files, the columns have grown too big.
Upon inspecting the html code, we can see that the there is an extra tr element at the end of the table, with the height "0". Deleting this element fixes the issue.