Since you did not mention the DFM version you were using, I assumed that you are using the latest 4.0 version.
Can you please follow these steps to help debug the issue:
1. Create a file called testpoints.txt in log directory (/opt/NTAPdfm/log on linux) with the following content:
testpoint -m pmhandlers -n xml-trace -e 1 -r 1
2. Wait for say 10 minutes.
3. Send us the contents of xml folder that got created in log directory (/opt/NTAPdfm/log/xml on linux)
4. Delete testpoints.txt file created in step 1
5. Create a database backup using "dfm backup create missing_data"
6. Send us the missing_data.ndb file created in data directory (/opt/NTAPdfm/data on linux)
7. Send us the contents of log directory (/opt/NTAPdfm/log on linux)