Update app notification does not work

Previously, when there was an update in the in-NC application, the bell icon in the top bar was attached with a badge and informed. However, I can not know the existence of updates unless I enter the setting monitoring item or App menu. I sometimes be rarely informed with bell icons. The update of NC itself is notified at all. There is no way to know only in the setting summary item. *I have set up a notification group.
This is not a fatal problem, but I want to solve it. This seems to be occurring from NC14.

Nextcloud / CentOS 7.5 / Nginx 1.13.8 / PHP 7.1.24