Good morning, @kjkleiss ...
This is just a guess on my part. Take a look at "Answer 1" and "Answer 4" which were marked "Correct". If you were to draw a vertical line right up against the "F", you would see that they appear to start at the same space. Now, draw a vertical line at the start of the ones for "Answer 2" and "Answer 3". It almost appears that for the ones where "You Answered", those appear to have a single space in front of them. An example would be:
" (ClO4)-1" instead of "(ClO4)-1"
Since the one with the space was not given as a possible solution, then Canvas would have marked it incorrect. Again, just a theory based on what you've provided in your screen shot.
Hope this helps a bit. Sing out if you have any other questions about this...thanks! Take care...be well.