BIRT 4.18 Windows, An error message is displayed when the generated Word document is opened.

[syc795]

I am using BIRT 4.18 on Windows, and I have found that if I use nested Grids and then generate a Word file (whether through preview or directly through the interface), I receive a message when I open the Word file saying "Word found content it couldn't read," asking me if I trust the source to open it. After confirming and opening it, it shows that "Sections and Heading 1" need to be fixed. Below are my rptdesign file and the generated Word document. Please help me to check.

new_report_5.docx
new_report_5.rptdesign.txt

[merks]

Have you tried the latest release?

https://download.eclipse.org/birt/updates/release/4.23.0

[syc795]

Thank you for your help.
Yes, 4.23 is ok, no issue. But why, is there any workaround in version 4.18?