Simulink error - Could not find library 'simulink/Sources/Sine Wave (for all the basics simulink blocks)

This message finds you well. I don't have experience working with Matlab, and I am trying to make a program on Simulink, but when I try to insert the block Sine Wave on the project, it appears an alert which says that the library was not found: "Could not find library 'simulink/Sources/Sine Wave" (The problem is for all the basics simulink blocks). Besides, when I check the Matlab interface it shows another problem: "Warning: Attempt to load model file 'C:\Program Files\MATLAB\R2019b\toolbox\simulink\blocks\library\simulink.slx' recursively ". I would really appreciate if you could help me to solve this issue. Thanks in advance.