zabbix proxy dont send the firts data item to server.

1- Create an item on server for host monitored by proxy
2- wait to proxy reload configuration

3- the firts itens send by zabbix_sender return processed, insert on sqlite but dont send to server.

Ex:
execute a script to send data every 1 second.
#====================================================
while true ; do date; /usr/bin/zabbix_sender -z xxxxxxxxx -p 10051 -s PROXY-UNIX -k test-zabbix_sender -o "test $(date)" ; sleep 1 ; done
#====================================================
Sex Ago 4 19:21:23 BRT 2017
info from server: "processed: 0; failed: 1; total: 1; seconds spent: 0.000024"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:24 BRT 2017
info from server: "processed: 0; failed: 1; total: 1; seconds spent: 0.000024"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:25 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000041"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:26 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000039"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:27 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000038"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:28 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000032"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:29 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000032"
sent: 1; skipped: 0; total: 1
Sex Ago 4 19:21:30 BRT 2017
info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.000036"
sent: 1; skipped: 0; total: 1
#====================================================

the first processed are "Sex Ago 4 19:21:25 BRT 2017"

Proxy reload on 20170804:192118, and receive the item trap
#====================================================
8149:20170804:192118.387 received configuration data from server at "zabbix-server.portoseguro.brasil", datalen 27201058
#====================================================

Proxy Sqlite
#====================================================
sqlite> SELECT * FROM proxy_history WHERE itemid=2836052;
1472314372|2836052|1501885285|0||0|test Sex Ago 4 19:21:25 BRT 2017|0|89233384|0|0|0|0
1472314687|2836052|1501885286|0||0|test Sex Ago 4 19:21:26 BRT 2017|0|95870129|0|0|0|0
1472315142|2836052|1501885287|0||0|test Sex Ago 4 19:21:27 BRT 2017|0|102562265|0|0|0|0
1472315700|2836052|1501885288|0||0|test Sex Ago 4 19:21:28 BRT 2017|0|110891383|0|0|0|0
1472316353|2836052|1501885289|0||0|test Sex Ago 4 19:21:29 BRT 2017|0|118340489|0|0|0|0
1472316528|2836052|1501885290|0||0|test Sex Ago 4 19:21:30 BRT 2017|0|125114812|0|0|0|0
#====================================================

MySQL Zabbix Server
#====================================================
mysql> SELECT * FROM history_text where itemid=2836052;
---------------------------------------------------------------------

---------------------------------------------------------------------

---------------------------------------------------------------------
5 rows in set (0,03 sec)
#====================================================

On this test i lost the first value, but sometimes the lost is bigger than one value.