Curious if you changed TTL (Time to Live) to a lower number before you made your changes. Otherwise your old DNS entries may remain cached in the internet for days. TTL tells the DNS servers how long before the remote entries expire.
Thanks for your response. We did set the TTL time to 10 minutes when we made the change, which was the minimum permitted by our DNS provider. Unfortunately, that did now seem to help the app framework (although accessing the new server outside the app framework worked perfectly).