MATLAB: How to fill the area between two plots in a loglog plot

MATLABpatch

I am trying to fill in the area between the confidence interval of my pwelch. This is the code I am using: 
[px1, f, conf1] = pwelch(det_total_b1,hanning(nfft),round(0.5*nfft),nfft,fs,'ConfidenceLevel',0.95); 
[px2, f, conf2] = pwelch(det_total_b2,hanning(nfft),round(0.5*nfft),nfft,fs,'ConfidenceLevel',0.95); 
[px3, f, conf3] = pwelch(det_total_b3,hanning(nfft),round(0.5*nfft),nfft,fs,'ConfidenceLevel',0.95); 
[px4, f, conf4] = pwelch(det_total_b4,hanning(nfft),round(0.5*nfft),nfft,fs,'ConfidenceLevel',0.95); 
loglog (f,px1,'Color',[0 204/256 102/256])
hold on
loglog (f,px2,'Color',[1 102/256 102/256])
loglog (f,px3,'Color',[0 128/256 1])
loglog (f,px4,'Color',[1 153/256 51/256])
patch([f fliplr(f)],[conf1(:,1) fliplr(conf1(:,2))],[0.85 0.85 0.85])
set(gca, 'XScale', 'log', 'YScale','log')
But instead of filling the area in gray, what it does is plotting the confidence interval limits as black lines (figure attached). I can't understand why it is doing that.
Thanks for the help in advance!

Best Answer

You have one fundamental error. Your matrices are (Nx2), so using fliplr on each column is pointless. You need to use flipud and vertically concatenate them: 
patch([f; flipud(f)],[conf1(:,1); flipud(conf1(:,2))],[0.85 0.85 0.85]);
Perhaps the problem is with your data or what you are plotting, although when I simulated it with random (rand) column vectors, the data were real and greater than zero.
Using patch with loglog plots works in other contexts, for example: 
x = sort(rand(10, 1));
y = sort(rand(10, 1));
figure
patch([x; flipud(x)], [y; flipud(y+0.2)], 'r')
set(gca, 'XScale','log', 'YScale','log')
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