On installs where iface reported by "route" command is not the same with ifcfg-iface (pxpy instead of enpxsy or ethx) fail2ban will not start. Does not matter if biosdevname=0 or net.ifnames=0 on the kernel line. Tested this on real hardware and on VirualBox too.
From /var/log/messages:
fail2ban-client[2804]: ERROR Directory /var/run/fail2ban exists but not accessible for writing
Fail2ban is ok on any other install.
C. Sava