While using the latest version of Aspose.Words i.e. 13.6.0, I managed to reproduce this issue on my side. I have logged your problems in our bug tracking system. The ID of your issue is WORDSNET-8676. Your request has also been linked to this issue and you will be notified as soon as it is resolved. Sorry for the inconvenience.
Thanks for your inquiry. Unfortunately, at the moment we cannot provide you any reliable estimate and this issue is not likely to be fixed in the near future. The implementation of this issue has been postponed till a later date and we cannot push it into production right now because there are many other important issues we have to work on. We will inform you via this thread as soon as this issue is resolved. We apologize for your inconvenience.