I just tried updating using the x86_64 packages from the koji site for check-mk and check-mk-livestatus. I am still getting the below error when trying to start Nagios with the broker enabled:

Error: Could not load module '/usr/lib64/check_mk/livestatus.o' -> /usr/lib64/check_mk/livestatus.o: undefined symbol: last_command_check

Below is the broker line I use:

broker_module=/usr/lib64/check_mk/livestatus.o /var/spool/nagios/livestatus.sock

Output from RPM:

rpm -qa | grep check-mk

check-mk-1.2.6p16-1.el7.x86_64

check-mk-livestatus-1.2.6p16-1.el7.x86_64

Publishing a fix during the next hour, please give 1.2.6p16-2 a try as soon as it's built. Thanks!