I concluded that the main issue was how she provided feedback to me (although not responding to my emails was also difficult!). Most of the right side column of my paper was filled with comments, so I was overwhelmed right away. The tone was often harsh and sometimes condescending. For example, "I don't know what you mean" or "Actually this is incorrect" were typical but I also got a "I believe perhaps you are not aware of what a powerpoint presentation is to consist of" (which is a pretty horrible sentence and we won't even get into how I present on creating effective PowerPoints).
I don't recall ever getting this kind of feedback in all of my years in school, much less as a doctoral student! Ouch.
Coincidentally, I also came across a blog post on criticism and ineffective feedback which I think applies perfectly to this situation. The author, Kate Heddleston, defines criticism as "feedback that finds something wrong with someone, especially without giving them indications about how they can fix their behavior."
The way this instructor provided "feedback" often made me feel like it was about me more than the content. She rarely provided an explanation or suggestion for improvement. This type of feedback made me feel defensive, especially when she just said I was incorrect. I looked back on my sources and, for almost all of her comments, still felt I was right. I thought it was just me, but Heddleston says that this is a normal reaction to critical feedback.
"When people receive criticism, they perceive it as an attack and their gut reaction is to defend themselves....People are so eager to avoid criticism, critical feedback is more likely to make a person quit something than change their behavior."
I emailed my instructor for clarification, but she didn't reply for three days. On Friday, I realized I still hadn't heard back from her so I emailed her asking if we could chat on the phone. She replied to this email uncharacteristically quickly to say she couldn't because she has a full-time job (hmmm?) and she directed me toward her office hours, but they had passed for the week. So, I had to do my next assignment without clarification on the first, which was really uncomfortable.
Heddleston says that critical feedback affects performance negatively. She provided a story about her friend, a motorcycle rider, whose first pit guy told him everything he was doing wrong. The rider became tentative, got into accidents, and didn't like the sport as much anymore. However, his next pit guy was super positive, emphasized his assets, and helped him understand how he could improve through constructive feedback. This time, her friend performed better and enjoyed it much more.
The weekend I had to complete my next assignment without knowing why I did so poorly on the first was horrible. I had difficulty doing anything and over thought all of my work. I researched and read for hours and hours, with very little output because I doubted most of my conclusions. Eventually I just started to run out of time and submitted something that was mediocre and I knew it. The feedback on this assignment was worse than the first and actually brought me to tears! Then I felt silly for being so upset.
Thankfully, I worked with my advisor and was assigned a different instructor. My classes are all 1-1 mentoring with the instructor to provide maximum flexibility for students and, although I generally like this model, it is incredibly difficult when a situation like this occurs. My new instructor is fantastic and I'm back to being an A student which makes me think the problem was not me :) She verified that in a few parts of my papers I actually was correct (the other instructor was wrong!) and in a few places my wording was a little strong and I should have hedged a bit more (it may be customary to...). So, at least there is a happy ending to this story!
I recommend reading Heddleston's blog post, especially if you're interested in gender inequality in giving critical feedback (spoiler: women receive significantly more criticism than men). She ends with a suggestion to "Give positive feedback to bolster people's confidence, ask questions when you want to spark a discussion, and give declarative feedback to help people improve and change."