[WP-UserOnline] Does not see online users

After I installed 2.80 it killed my wp_useronline database and does not write a new one. Hm, deactivated the plugin and then I tried this: https://forums.lesterchan.net/index.php/topic,3011.msg22546.html#msg22546 and give myself a new database. After activation of the plugin it deletes the database again! Nor I am shure, it is WP-UserOnline and nothing else.

With 2.73 I fixed it anyway, but now I have no idea. ??