Created attachment 31207 [details] the diff for this patch Currently, a style is only applied to a cell if the cell style attribute ("s") is present. Following XSSFCell.getCellStyle(), if the attribute is not present, and there are are more than 0 styles in the styles table, we should use the default (0) style. This patch may also be the resolution for https://issues.apache.org/bugzilla/show_bug.cgi?id=55648.
Any chance you could work up a short unit test to go with the patch, which shows the problem + ensures it is solved?
Created attachment 31211 [details] diff for test case
Created attachment 31212 [details] test file to go in test-data/spreadsheet
Please find a diff for the requested test case and an XLSX file used by the test attached.
Thanks for the patch and testcase, this is now included via r1563470, it will not be contained in 3.10, though, as we already cut that version before.