Welcome!
Of course they could have. That being said, though, the results are not totally inconsistent with your academic experience. PRI is a mixed measure, combining fluid reasoning (highly correlated with abstract thinking and mathematical reasoning), and visual spatial thinking (sometimes associated with mathematical thinking, but not always). You did well on the tasks associated with math (matrix reasoning and arithmetic), and less well on those associated with or affected by speed (block design, visual puzzles, coding, symbol search). Based on your PSI, you probably did not receive many bonus points for speed on block design, and may have received no credit on some of your responses in visual puzzles, if they were past time limits. Also, there are many, many items on VP, so even if you did a lot of items, there may have been others that you didn't see.
Net, your scores are not unreasonable for someone with your academic history. They may be a little bit of a low estimate, but fatigue usually affects WMI and PSI the most, so, if anything, it might have made your ADHD stand out more.
