pbaspect not working with larger aspect ratios

Hello! I would like to have my aspect ratio of the figure to be [x,y,z] [7 7 1]. I tried using pbaspect, and it works with numbers such as [3 2 1], but I can't get it to work with my desired input. I tried decimals, and that also failed. Am I missing something obvious? Is there another way around this? Any and all help is appreciated.

Thank you!

[X, Y, Z] = meshgrid(x,y,z);
[faces,verts,colors] = isosurface(X, Y, Z, data, 0.5, Z); 
hold on
patch('Vertices',verts,'Faces',faces,'FaceVertexCData',colors,...
    'FaceColor','interp','EdgeColor','interp')
view(-15,10)
axis vis3d
colormap jet
xlim ([0 512])
xticks([0 100 200 300 400 500])
xticklabels({'0', '14','28', '42', '56', '70'});
yticks([0 100 200 300 400 500])
yticklabels({'0', '14','28', '42', '56', '70'});
ylim ([0 512])
zlim ([0 150])
zticks([0 50 100 150])
zticklabels({'0', '3.5','7', '10.5'});
pbaspect([7 7 1])
hold off