It is an environment with Zabbix server No. 1 and No. 2.
Since I changed the setting of template A of Zabbix server No. 1, I exported template A from No. 1 and imported it to Zabbix server No. 2.
As a result, the screen goes blank. There are no errors and the template is not updated.

1600 hosts are using template A.

I manually changed the settings of Template A on No. 2. Then the update is completed normally.
However, updating by import causes problems. Is this due to too many hosts being applied?