A CWOF can definitely get you a suitability denial, it will depend on the CoP.
The Process has the state do their check and then the CoP gets a final shot at using sutability. No reason to use suitability if someone fails the background check. Doing it in this order just makes it easier... for the CoP.
It sounds like the OP was told the state check went through and now the Chief may want to take a shot at it.
@Len-2A Training advice is probably the best you'll get, but it's likely the Chief has his own ideas of what gets a suitability denial and the decision has already been made.
Let me know how it goes, PM if you prefer, I ended up moving to NH after my suitability denial (after a bunch of years). It was also based on a CWOF (15 year past dismissed, single arrest in a lifetime). I'm still pissed at my lawyer, could have easily won but money was tight and he told me "it's meaningless, it will have no impact on your life". Scary part is that lawyer is now a district court judge in MA.