Cut/Paste and Update Values between two sheets (losing rows)

Hi, sorry if it took me long to answer,

i've managed to fix this issue by calculating a new lastrow

    Dim LrDepartment5 As Long
    LrDepartment5 = Department.Cells(Rows.Count, "B").End(xlUp).Row
    
        For m = LrDepartment5 To 34 Step -1
  
If Department.Range("C" & m).Value = "" Then
Department.Range("C" & m).EntireRow.Delete

and by splitting the file in several calculation steps.

Many thanks,
Picsou