Hello,
What you found turned out to be a bug. The fix for this is already done and will be included in the next release.
Why we are disabling all datasources by default is because each virtual user in LoadUI is not supposed to use different credentials, acting as multiple users. Instead LoadUI makes data sources be shared cross different virtual users making each new virtual user taking the next value from the data source. This sharing of datasources actually broke your test which used a data source to build a single request.
We fixed this by adding a setting for this in the SoapUI Runner, enabling you to choose if you want the sharing behavior or let it be decided by the SoapUI project.
Thank you for reporting this!
Regards,
Max