Check your printhead height.
I know, it doesn't relate to Flexi. Buuuuuuuut, I know of a similar incident troubleshooting a printer where the machine adjustment was
adamently ruled out...
names withheld.
...until,
and I'm not admitting guilt, someone checked the printhead height.
Other than that, I'll
adamently deny knowing anything more about how to troubleshoot the issue.