Odd Quotation Mark Behavior

Scrivener 3.1.5 (12258); MacOs 10.15.6. I notice sometimes that a quotation mark is highlighted after typing it, but I didn’t select it. The next character I type is often an optional variant. Shift-quote Y yields this: "Ÿ (option-U, Y). ‘Edit > Substitutions > Smart Quotes’ is not selected. ‘Preferences > Corrections > Punctuation: > Use smart quotes (“ ”) in new projects’ is selected. I cannot change the behavior unless I restart Scrivener.

Is there some keyboard shortcut that I am typing without realizing it? I have checked the keyboard shortcuts and don’t see anything to cause this. Any help is appreciated.

Update: Restarting Scrivener now only eliminates the option-character behavior. Quote marks are still highlighted, and it seems that the character is a highlighted straight quote that changes to a smart quote and the highlight goes away. Pressing space after a close quote requires two spaces: one to remove the highlight; one to create the space.

Solved. I have two keyboards installed: US and US International - PC… The International was selected. Why, I don’t know, but I discovered it when i typed 'e and got é instead. I removed the international keyboard to prevent inadvertently selecting it again.