KiCAD Schematic symbol error

I’m using KiCAD KiCAD 5.1.6 Stable version.
Recently have created a symbol and added in schematic pages and went back modified symbol and when I updated in schematic , symbol is lost in sch with question mark.

This happens when the symbol library is not in the project library preferences


And if you did not take care about the cache and rescue process (libs missing is necessary for this to happen but not enough on its own)