As somebody who makes cheese in their spare time, this is something that I have looked into a little - I am however not an expert!
The general received wisdom in the cheesemaking community is that homogenization and pasteurization are processes that tend to reduce the ease and reliability of curd formation - something I have experienced and I think most people accept as being true. Greater reliability of curd formation can be achieved by adding calcium chloride into the milk and once again I think most people accept as being true. The most common explanation for this behaviour is that heat and homogenization reduce levels of calcium (and phosphate) in milk.
Logically however, the concentration of calcium cannot change unless either the volume of liquid is reduced (thereby increasing Ca concentration), Ca is somehow becoming magically able to jump out of our milk or our terms are somehow inaccurate. Of course the latter is our issue... Whilst overall levels of calcium (and phosphate) ions in our milk are unaffected by heat, the levels of soluble calcium and phosphate is...
Some very old data (1920s) that I came across showed that milk heated to around 100C (for 30 mins) can result in a 10% loss of soluble calcium. I would doubt that pasteurization would result in 6-7% loss of soluble calcium as cited, but perhaps combined with homogenization and a very old but not quite sour sample, you might get something in that order perhaps?