I'm having the same issue. I can sometimes change the infant's diaper successfully, but the toddler has issues every single time. Towards the end of the diaper changing animation, the Adult suddenly T poses and the infant/toddler goes on the floor and it throws an exception. The diaper is actually changed, however, as my toddler gets the "fresh tush" moodlet. I have tried moving the changing table and I tried a different changing table, but it still happens.
This is what the Better Exceptions reports I get say:
Exception in Sim Timeline: Exception running Element (AttributeError: 'object_TableChangeDiaper' object has no attribute 'has_buff')
This is what shows up on the last exception report from MCCC:
