If restart zabbix agent on windows more time - it is stop send data to zabbix server.
If after that, stopping zabbix agent and see netstat - can see many CLOSE_WAIT or TIME_WAIT state of connections. And if try to connect to 10050 from zabbix_get - connect success, but data not received. telnet - also.
In this case help only reboot or set another port to list connections in zabbix agent config file.