Same here with both, DPP3.... and DPP4....
But I also have issues with another app on my NAS that cannot handle jpegs exported with LR5.5.
I did export the same image with the same preset in LR5.4 and 5.5. Visually you can already see a x/y shift between both jpegs and imagemagicks compare did also show differences.
Others over at canonrumors compared exif info for 5.4 and 5.5 and did find differences. Someone also stripped the exif info from a 5.5 export and I tried to use this file on my nas but this did not help.
I have now uploaded pictures from 5.4 and 5.5 to the adobe "bug" report site ad asked them to look at least into it.