The other thread has a 250mg/ml recipe...you are trying 400mg/ml. I am guessing the mg/ml concentration is too high.
I attempted test prop over the weekend at 200 mg/ml and failed miserably. I use a lot lower of BB % than you(just personal preference) but still at some point the hormone will just not hold at too high of a concentration. I have read a lot about how high you can go, but I guess I wanted to see for myself. There are not a ton of homebrewers and sometimes people repeat what they have read and never actually tried it, so I went for it. There are definte limits.
Some UG put out very high dosed mixes and frankly they are most likely underdosed because at some point even with a ton of solvents the formula will not work.
Good luck!