It seems to be a weird CalculiX bug or actually a regression. Try running the exported .inp file in different standalone versions of CalculiX (and with different solvers) to see when it stopped working. You can download old releases of ccx by just changing the number in this link: http://www.dhondt.de/calculix_2.21_4win.zip
Instructions how to run jobs with standalone ccx: Using standalone CalculiX
Then it would be best to create an issue in ccx GitHub repository: Issues · Dhondtguido/CalculiX · GitHub