an example result:
knime://knime.workflow/..\Example_Data\file1.mzML
The first part knime://knime.workflow/ seems to only work with forward slashes and is generated correctly. The rest of the path is generated differently depending on the OS and uses \ on Windows. The node does not run with a mix of / and \.
Input Files does not allow to paste or manually edit the file paths, so it is not possible to fix these paths in the KNIME GUI.
Workaround: fix the file paths with a text editor directly in the settings.xml file of the node.
A workflow that was set up with relative paths only containing / (e.g. on Linux or using the workaround) runs fine on Windows.