To workaround:
press "Ctrl-S" before clicking "Save & Exit".
The problem is due to the failure of "Save & Close" to save the UIDoc, resulting in no change to the body field. To fix: In Shared Code -> Actions -> Save & Exit, replace the "Click" method with this:
Sub Click(Source As Button)
Dim ws As New NotesUIWorkspace<br/>
Dim curruidoc As NotesUIDocument<br/>
Dim currdoc As NotesDocument<br/>
<br/>
Set curruidoc = ws.CurrentDocument<br/>
Call curruidoc.Save<br/>
Set currdoc = curruidoc.Document<br/>
Call currdoc.Save(False,False) <br/>
Call currdoc.ReplaceItemValue("DeleteFlag","0")<br/>
Call currdoc.Save(False,False) <br/>
Call curruidoc.Close<br/>
End Sub
BTW, this ALSO fixes a problem with creating Follow-Up To-Dos after the fact.