Scenario:
You have one clip with multiple effects;
You select this clip, and Copy (Command-C);
You select multiple clips and Paste Attributes (Command-Shift-V).
What is supposed to happen is:
a) a window appears allowing you to check or uncheck any of the applied effects
b) when you confirm, the checked effects are pasted onto all the selected clips (in addition to whatever effects those clips might have already)
Is this what you are doing, but then not all the clips receive the intended effects?
I have not experienced this, and I cannot reproduce it.
I suppose you are up to date, since your profile says M4 Max - Sequoia 15.5, FCP 11.1.1? Or some other versions?
If the problem is repeatable, I'd start by deleting preferences. To delete preferences, hold down command and option while starting the application and click Delete Custom Settings. The application will start with default settings and open an "Untitled" library. Adjust the settings, reopen the library you were working, and see how it works now.
If the problem persists after deleting preferences: Please run Etrecheck and post its full report here.
Use the "additional text" button and paste the report into the text box.