I'm having a the same problem using the attched file. I started with a test harness, but received error 1103. I found that it happens with no custom code directly in CVT Load Tags VI. The XML is structurally correct (verified in both TCE and by viewing raw XML in Firefox).
Steps to reproduce:
1) Locate the VI Load Tags in the CVT libary
2) At the front panel, run the VI
3) when prompted (by file path control), navigate to the attached configuration.xml and select OK
4) verify code and message in error output
Platform spec:
Windows 7
LabVIEW 2014 (32-bit)
CVT v3.3.0.13
TCE v2.1.1
Update: I forgot to note that the actual error text from Load Tags simply points to Unflatten From XML in Current Value Table lvlib.