I've been running a bunch of Button vs BB sims in PIO and am trying to understand why PIO checks back some strong hands on dynamic boards? Example of a button vs bb 2.5x open/defend:

Flop Td7c6c - PIO decides to bet 66/77/67x almost pure while x back TT (30%), T7x (50%), T6x (pure)

Can anyone help shed light on why PIO decides to check back some of it's strong value range (2pr+) on this flop? A side note question is why slowplay T7x but pure bet 67x?