Sadly, sounds like the issue is probably at blizzard's side. Workaround would be way too time consuming for me currently. (When I made the addon I didn't have fulltime job yet.)
I'll gladly accept anyone as cooperator on the addon if they are willing to help and provide decent fix. But from my side, don't really expect anything unless something in my time schedule changes. Sorry.
Until I'll release it as a feature (to disable trash drops), which might take a while. You can blacklist all items from trash in dungeons you are working on. Not the greatest solution, but at least something.