Hello i need your help  on how i understood plate moment signs, iam attaching my staad model for reference

Staad model and we may take group S1 for demonstration and Mx values

communities.bentley.com/.../640386.Structure1.STD

From what i understand the moment should be negative((hogging - top moment) where slab and beam meets and should be positive (downward - sagging) on the midspan, if you refer the below diagram

i could expect that plate no 46 and 86 could have negative moments(hogging) while interior plates could have positive moment(sagging) but for my case all the results has the same values, why does it look like this?