We managed to replicate the problem of additional white symbols in our environment. It has been logged under the ticket ID PDFNET-43420 in our bug tracking system. We have linked your post to this ticket and will keep you informed regarding any available updates.
Would you be so kind to provide us with status on the PDFNET-43420 issue?
We regret to share that mentioned issue is not yet resolved due to other high priority issues in the queue. We will surely let you know as soon as there is any progress made towards resolution. Please spare us little time.
We are sorry for the inconvenience.