The column name "".$_SESSION['WADA_Insert_products']."" was not found.
Nothing is inserted after starting from scratch.
On the update page there is also a red ! next to "Manage Relational Table"
For the topic of nothing being inserted:
Just found out that the MRT is put BEFORE the Insert Server behaviour, so the session variable cannot be retrieved in time.
I'd call this a serious bug in the code.