Pentaho Data Integration: Table Lookup Step throws "Cursor has been closed."

Question

I am having some difficulties with a table lookup Step in PDI that gets data from a Filemaker 16 database.

First problem was that suddenly PDI (Kettle) did freeze when I opened the step. This was reproducible and happened every time. I did some research and saw that the Filemaker driver for Java (fmjdbc.jar) was quite old (from 2010) so I replaced it with the one from Filemaker version 16. Now I could again access the lookup step, but all my transformations that worked fine so far now throw the error

[FileMaker][FileMaker JDBC] Cursor has been closed.

The used PDI version is an older one (5.01) for various reasons, but I tried with newer versions (7 & 8) and the problem was the same.

I looked for the error message but did not find anything that was helpful in this case, as I am not able to change the way the lookup step tries to retrieve the data. I tried enabling cache in the step, but that did not help.

Thanks in advance for insights.