Zend certified PHP/Magento developer

“This product does not exist” error each time I create a configurable product [2.3.3]

I try to create configurable products in magento 2.3.3 using 2 attributes: color and shipfrom

I simply add the attributes, the values, then save.
Just after saving I get the following error:

enter image description here

I cannot edit the configurable product if I try to, resulting in the same error.
However delete is working.
That seems odd as you would like to be able to change the list of associated products sometimes. Any idea what is the issue here ?