External Storages appear and disappear in the webUI

I want to use “External Storages” to share data in FreeNAS with NextCloud. But after installation of “External Storages” App under admin account. I click the External Storages widget in the left panel, it appear first and then disappear.

Here is a short screen Record for this error: nextcloud external storages disappear

I run nextcloud in FreeBSD 11.1-release, and i am using iocage plugin to install it.

Main Nextcloud Configurations:
nextcloud: 13.0.0
Database: mysql
web engine: nginx

I am not familiar with nextcloud project and php programming, can anyone help me to locate the error log related to this error. Thank you.