I have responded to all my messages, but it shows that I have not. I have gone back and doubled checked. Sometimes I will respond through the app on my phone, other times I do from my computer. I do respond within a very short time as most messages are about a personalized item. Don't know what else to do.
Have you checked your messages CSV to see which one(s) Etsy thinks you missed?
There was a period of time (I think in December) that if I responded using the app it would still show as a new message on desktop. I had to reply again on desktop for the Etsy system to acknowledge I had responded. I don't know if it would help your situation, but I have found it best not to bounce back and forth between the app and desktop if possible ( I know sometimes it isn't). Sorry that you are having issues. Check that CSV!
the app is unreliable.
not breaking news.
Check the CSV for when new messages arrived and you answered. It will tell you the ones missed.
Sometimes messages end up in spam. You need to look there for new messages that may be legit. If not answered they count against you.