Total mystery how this happens, but if the system in fact knows what the values are (States, Roles, etc.) then with enough fooling back and forth between Constant and Parameter, it just kicks in. But - It's very hard to get the system back to accepting text for things that should not be drop-downs.
Query Builder is very helpful but has essentially no documentation and is very quirky.
One other note - be careful about using the System Date function (example: use Time Difference days to subtract System Date - Created for any object). The system Date is considered (always) to be 5pm yesterday, resulting in negative results for the time since creation for creation that occurred this morning.