Ok thats a bit wierd.
I don't know if it matters or if its a typo but you have a space before field Logtime.
You can try enabling the debug mode and the log files on the agent will probably tell you whats wrong. but remember to turn it off afterwards as it can generate much logs. The log file is located here C:\ProgramData\VMware\Log Insight Agent\log on the agent server and called liagent_Date.log
This is the config i'm using. I have tried to make the fields unique with a prefix WinFW_. I don't really know if that matters.other than that it seems to be the same as yours except for the timestamp parser.
[filelog|WindowsFirewallLogFile]
directory=C:\Windows\System32\LogFiles\Firewall
include=*.log
parser=WinFWLogParser
tags={"label":"windows_firewall_logfile"}
[parser|WinFWLogParser]
base_parser=csv
fields=WinFW_Date,WinFW_Time,WinFW_action,WinFW_protocol,WinFW_srcip,WinFW_dstip,WinFW_srcport,WinFW_dstport,WinFW_size,WinFW_tcpflags,WinFW_tcpsyn,WinFW_tcpack,WinFW_tcpwin,WinFW_icmptype,WinFW_icmpcode,WinFW_info,WinFW_path
delimiter=" "
debug=no