Hi - I’ve used MainWP for many years and had this notification several times. Usually I manage to get rid of it … not so this time.
This is v. 5.3.3 on both the main dashboard and the child plugin. I not only deactivated and reactivated the plugin, I even completely removed it from the WP installation, deactivated the cache plugin (LightSpeed), ran WP-Optimize, and then newly installed the plugin. I still get the same message about no detection upon reconnecting from the main dashboard.