The file exported from the Sigma Data Center 5.7 cannot be imported directly into Garmin Connect Web. We receive a generic and unusefull error message.
The problem is that the "<Creator xsi:type="Device_t"><Version>" tag (at the end of the file) has no <BuildMajor> or <BuildMinor> tags.
The addition of these 2 tags allows the import of the file without problem.
They should be optional!