Classes not available to select in character blueprint

Dear all,

I have a projectile class build in c++ from which i create a blueprint class. My character isc capable of spawning one projectile class object.
When i go to my character and try to select the projectile class in the blueprint details, no classes are shown… I need to close the whole unreal editor and reboot. After this the two class (c++ and BP) are there.
https://imgur.com/a/eZMrerT

Is there a way to fix this?
Kind regards

Roberto