Thanks for your inquiry.
Aspose.Words supports all major OOXML versions for example OOXML ECMA-376 and OOXML ISO/IEC DIS 29500. OOXML WordprocessingML documents most often come as DOCX files, which are ZIP packages and Aspose.Words does support DOCX format. However, Aspose.Words does not support ISO/IEC 29500 Strict OOXML version.
I would suggest you please use the latest version of Aspose.Words v13.3.0
. If the problem still remains, please attach your input Word document here for testing. I will investigate the issue on my side and provide you more information.