It's the PC that makes the cream soft. If it doesn't cover the outside then it's little "roots" don't invade the cheese and break it down.
PC likes a fairly high humidity to grow, however if the temperature is also high then you end up with slipskin as the tendrils don't grow all the way to the center.
My second batch I kept at 9C and they took an extra week or two to fully mature but compared to my first batch, which had matured only half way through, they were great.
The brownish paste may have been B Linens.