Removing the bins argument from the hexbin generator seems to fix the plot scale. I don't understand why, maybe because some data was outside of the bin limits?
hexbin = ax.hexbin(x=player_sorted.LOC_X, y=player_sorted.LOC_Y, C=player_sorted['Relative Percentage'], gridsize=50,
mincnt=2, edgecolors='white', cmap='RdBu_r', vmin=-0.1, vmax=0.1)