category subscription error

Hey I have just downloaded the plugin on a fresh wp site.
and installed your plugin and did all the steps mentioned in the docs and video.
he problem is that when I add a new device and set some category for it in “All Devices” section under “Subscribed To” column the cells are empty “__” .
there for when I go to “Push Notification” section the category tab that should be shown on the left is also not shown!

hope I can get some help!

Thank You For Your Efforts!!

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