The sysusers_create_compat macro was added to epel-rpm-macros 7 and 8, to support current packaging guidelines (see bug 2000406). However the version that was added does not properly handle secondary group memberships (lines beginning with 'm'). This was later fixed for Fedora here: https://src.fedoraproject.org/rpms/systemd/c/f27d461663bec17ad64422682f260f0020ccc7f7 Please either backport this single change to EPEL 7 and 8, or (if possible) update the entire macro.
I submitted https://src.fedoraproject.org/rpms/epel-rpm-macros/pull-request/77, but it needs to be tested