I’m new to machine learning so I have been playing around with some of the models trying to get a better understanding.

I am doing the Kaggle House Prices competition to practice my machine learning skills. I preprocess the data and then use cross validation to test a couple of different models to see which one performs the best. Unfortunately, although I receive normal looking results for the majority of the models, the results I get for Linear Regression make no sense. I am posting my code and a picture of the results, the data file you can find in the link to the Kaggle competition. Can you please explain to me why I am receiving these results and what can I do to fix them?
Accuracy Scores Results