All I can think of is that the walls by default have a setting in properties listed as ‘d. Lower Exterior Face’ , This creates a exterior surface that covers the band (floor jst)… You may have changed that too small or need to increase it because you are using a deeper floor joist.
If that in not the case, then your math is wrong in Location settings. You have to reduce floor level settings to close the gap.
Jack zimmerdesign.com