issue parsing yang submodule on linux (but not on Mac)

ODL fails when parsing a YANG submodule on Linux (Ubuntu). The same submodule parses ok on a Mac. I'm using the same Opendaylight and Java versions on both (1.7.45 of the latter though I also tried 1.7.60 on Linux).

the modules appear to be correct:

we have a parent module and multiple submodules.

submodule 1 includes submodule 2 and then uses a grouping defined in submodule 2.

when parsing the module on Linux ODL complains about the grouping:

org.opendaylight.yangtools.yang.parser.util.YangParseException: Error in module 'tailf-ncs' at line 68: Grouping 'ssh-connection-config' not found.

logs attached.