It is possible you'll need to destroy and recreate the connection on the SIEM side. We've had to do that in the past.
You're on 80.20 so you've got the log exporter stuff built in now. So why not just Syslog everything? Check out sk122323.
Here's the cheat sheet (you'd need to run this command on every CMA):
cp_log_export add name McAfee-SIEM domain-server <domainX> target-server 10.10.10.10 target-port 514 protocol udp format syslog
You'll be prompted to restart the exporter and BAM. Syslog.
We've been very successful with this method on 80.10.