It may be too late to work , wish I had seen this yesterday.
I have had that happen a couple of times , I really think it has something to do with the milk as I had new rennet and cultures.
Anyway , it looks like a clean break but starts to break up when stirring , I add about 1/2 gallon of very hot water right away (for a 4 gallon make) , similar to washing a Gouda , it seems to help solidify the curds so you can separate and get them in the mold.
They stay quite small , but they do separate and sink , I have come out with something similar to a Gouda , quite good really.
I used tap water as hot as it gets , hope this helps.