Import bug - default category reset

[salouso]

Hello

Suddenly without having done any updates, I have a weird problem with imports (which I have done daily without problems for the past 2 years nearly). PS 1.7.6.7

I import a csv (or xls - same behaviour) with columns for product reference, quantity, price and weight. No other columns included.
The import runs smoothly and shows no errors... BUT:

On random products the assigned default category just gets changed to one of the former associated categories...

i.e:

Product A before import is in Category 1 as default and 5 and 10 as associated category.
AFTER the import product A is now showing default category as 10 and category 1 and 5 as associated.
Interestingly it always attaches it to one of the non-default categories.

It happens to the same products everytime, but sometimes it manages to get past the first 500 and sometimes it happens already in the first 500 products on the csv. Out of 5000 products it affects just over 600 products which I then have to re-assign to the correct categories after every import (which I do up to 2 times daily.....).

It happens with Debug Mode on and off, with non-prestashop module and overrides on and off, I have emptied cache via Backoffice and also manually deleted cache.
I have tried deleting the category it alwyays attaches the products to. Recreated that category and renamed it. Same thing happens again.

So far I believe that on import Prestashop looses the id_category_default and then just assignes the other id_category that exists on the product. Because if the product only is assigned to 1 category (id_default_category), everything is fine.


Please help 😞 I have spent the past 16 hours trying to figure this out.

Kind regards
Sarah