Sleepover shifts are supposed to come up as AM/PM/NS shifts on the Members App as this links to the members availability.
This can be configured within your Alloaction Master - Member Shifts
All Sleepovers need to be mapped to either am/pm/ns as those are the only types of availability on the app so this is why the SHIFT NOMINATED TYPE must be entered to one of those 3 options and will appear as that on the app - no SL or SO (depending on your code)