Chemist,
I now doubt if you really what you are talking about. Jones reagent is a standard oxidation reagent which works for a lot of substrates even strained molecules. Type chromium trioxide on Organic Synthesis website to know what I am talking about. The problem with Jones reagent is its selectivity. This is why PCC, PDC, Swern etc. was invented.
Hydrolysis of nitriles involve an excess of water. Jones oxidation is carried out with not much water. So it is really not likely that hydrolysis is the problem. Besides, the COOH peak can be easily seen in the 1H NMR spectrum.
My supervisor did 2 postdocs and one is with one of the editors of EROS. Using KMnO4 alone results on several oxidation problems. I agree with Sundberg and Carey on this. However KMnO4 in a solid support (like CuSO4, SiO2 or alumina) is know to be effective oxidizing agents producing high yields of the desired product.
But certainly, you have sone point on the nitrile coordinating with chromium so I owe one to you.
I already mentioned that SN2 reaction of dibromoacetone is problematic and here you are suggesting me to start with glycerol. It seems that you don't have a good eye for details.