Some kicad versions have a bug that could be responsible for what you see. Save your schematic (yes scary with the question marks i know) and close kicad. Then open it and check if that fixed it. If that is the case then you expirienced this bug. You should also check if you are on the lates stable version (5.1.4)
If this does not fix your troubles try to use a symbol from the system libs and see if it behaves the same way. If not check what the difference between the way you save the lib is.
Also do you get any error message when opening the schematic? If so what is the message?