Sorry for the late reply, I've been trying to look into this a bit. I've verified the same behavior that, on my windows machine, I can generate a Project level report via testrunner in XML format. When tryign to do this via Jenkins and testrunner, there is no project/report generated.
And then I saw the following information on Smartbear (https://support.smartbear.com/readyapi/docs/testing/reports/existing/about.html)
The problem was indeed the unix server lacking the font "package".
After installing the fonts required the Project Reports ( both XML and PDF) were generated accordingly.
Excellent find, @ecsmmek! Thanks for circling back and giving the answer.