ADO adLockBatchOptimistic allows updates on modified records - ado

Question

I'm begging for help, since I'm too stupid.
What I do:
Open connection to Access DB
Download Table to a Recordset
Disconnect the RecordSet
Update a record
Update the same record in DB (by another user)
Connect RecordSet back to DB
UpdateBatch affected record
Yesterday it was throwing an error that the record has been modified in the meantime.
Today it's updating the record without any issues.
I would bet my arm I haven't changed anything...
I open the recordset with following settings (first set them, then open):
.CursorLocation = adUseClient
.LockType = adLockBatchOptimistic
I beg everyone for help
Example Code:
Dim DB_FOLDER_PATH As String
Dim DB_FILE_NAME As String
Dim DB_FILE_PATH As String
Dim CONNECTION As ADODB.CONNECTION
Dim CONNECTION_STRING As String
Dim QUERY_STRING As String
Dim tmp_RS As ADODB.Recordset
Dim tmp_RS2 As ADODB.Recordset
DB_FOLDER_PATH = "\\XXXXX\userdata\XXXXX\home\Documents\Data Base\"
DB_FILE_NAME = "TEST"
DB_FILE_PATH = DB_FOLDER_PATH & DB_FILE_NAME & ".accdb"
Set CONNECTION = New ADODB.CONNECTION
CONNECTION_STRING = "Provider=Microsoft.ACE.OLEDB.12.0" & ";" & "Data Source=" & DB_FILE_PATH & ";" & "Persist Security Info=False"
CONNECTION.Open CONNECTION_STRING
QUERY_STRING = "SELECT" & " " & "*" & " FROM [" & "DATA" & "]" & ";"
Set tmp_RS = New ADODB.Recordset
With tmp_RS
.CursorLocation = adUseClient
.LockType = adLockBatchOptimistic
.Open QUERY_STRING, CONNECTION
.ActiveConnection = Nothing
End With
Set tmp_RS2 = New ADODB.Recordset
With tmp_RS2
.CursorLocation = adUseClient
.LockType = adLockBatchOptimistic
.Open QUERY_STRING, CONNECTION
.ActiveConnection = Nothing
End With
With tmp_RS
.Fields("FIELD_LONG_TEXT_PLAIN").Value = "ABC"
.Update
.ActiveConnection = CONNECTION
.UpdateBatch
End With
With tmp_RS2
.Fields("FIELD_LONG_TEXT_PLAIN").Value = "ZXC"
.Update
.ActiveConnection = CONNECTION
.UpdateBatch
End With
Best Regards,
Michal