In the past just after an SMS upgrade I've needed to execute an Install Database operation to get logging to resume, try that.
To check the status of your logging connections on the gateways try this command: cpstat fw -f log_connection
Next step is to check port 257 connectivity between the gateways and log server up on the SMS with: netstat -anp | grep -i -E "State|257"
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones