Menu entry lost

Although BackWPup is installed as a plugin, it is not shown anymore in the menu. It somehow disappeared and I cannot explain how it happend.

I installed plugins like ithemes Security and WP Super Cache, made some changes to the (child) theme. After it was gone I disabled and enabled it.

All backups are still there but the menu entry gone. Any clues?

https://ww.wp.xz.cn/plugins/backwpup/