Japanese characters are changed to ?????? in "Trigger Description" that have been created by the discovery. (fig1.png)
In MySQL, Japanese characters are changed to ??????. ("trigger_table_mysql.txt" and "fig2.png RED BOX")
If edit template item , The "??????" are changed to normal (linked change. and fig1.png BLUE BOX)
If delete the item and re-discovery, Reproduce any number of times in all of the items.
If restart the zabbix-server (systemctl restart zabbix-server) , then operating normally.
But It relapse after a few weeks.
It looks like