Are you connected to an organizational account of ArcGIS Online, and set as active portal in ArcGIS Pro?
Manage portal connections from ArcGIS Pro—ArcGIS Pro | Documentation
Do you have a consistent internet connection?
A couple of other things you could test
1. Close all ArcGIS Applications. Reboot your system. Open ArcGIS Pro, and Try sharing the layer.
2. Open a new ArcGIS Pro project > Add the layer to the new project. Try sharing it.
Could you share screenshot of the layer, in case the issue still persists?
Think Location