If you set the log export protocol to TCP, does it forward as expected?
From https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solut...
cp_log_export add name <name> [domain-server <domain-server>] target-server <target-server IP address> target-port <target-port> protocol <(udp|tcp)> format <(syslog)|(cef)|(splunk)(generic)> [optional arguments]
If the configuration has already been defined, it is possible to use the "set" command to adjust the configuration
cp_log_export set name <name> protocol tcp