Hello,
Thank you for your inquiry.
I tested your case with both
Free Spire.Doc for .NET(dll only) Version:9.9.7and the latest commercial version
Spire.Doc Pack(hot fix) Version:9.12.3, and reproduced your issue. I have logged the issue into our bug tracking system with the ticket number SPIREDOC-5048. Our development team will investigate and fix it. Once it is resolved, I will inform you in time. Sorry for the inconvenience caused.
In addition, we only upgrade our commercial products regularly, that means once the issue is resolved, we will provide you with a commercial version including the fixes. Hope you can understand.
Sincerely,
Annika
E-iceblue support team