To avoid table blocking issues, please change "GetNextReference()" of Table "Warehouse Setup" to a Non-Blocking No. Series.

procedure GetNextReference(): Integer
begin
LockTable();
Get;
"Last Whse. Posting Ref. No." := "Last Whse. Posting Ref. No." + 1;
Modify;
exit("Last Whse. Posting Ref. No.");
end;