The workflow to generate this bug wouldn't be typical but the bug should nonetheless be addressed
Steps to reproduce
-In Tests & Quizzes, create an assessment and select 'Multiple Choice' question type
-Proceed with the default selection (Single Correct BUT do not select 'Enable Partial Credit)
-Fill in the answer selections; make sure you select a correct answer
-Go back to the 'Answer' section and now select 'Enable Partial Credit'
-Scroll back down to the answer choices and you should see a '% Value' box next to each answer choice
-The '% Value" box for the correct answer choice is displaying '0' (actual) versus '100' (desired)