We were able to notice the issue in our environment using Aspose.PDF for .NET 18.12 and for the sake of correction we have logged it as PDFNET-45793 in our issue tracking system. We will further look into this issue and keep you posted with the status of its rectification. Please be patient and spare us little time.
We have logged above details along with the issue as well. This would really help us investigating the issue and resolve it accordingly.