@nokki00:
I've checked your website but I couldn't find why the system was not adding the category_pathway parameter to your URLs. So have activated back the "force canonical URLs for listings" option and entered the correct canonical URL with the category_pathway parameter in it (with the id of the category of the product) to your products and it's now working like you want.
@river:
No need to make any 301 redirects.
The old URLs of the products will still work even if the canonical URLs of the products have the category_pathway added to them.
And since you'll have the URLs with that extra parameter as canonical URLs, Google will just update the new canonical URL with that parameter next time it indexes the product pages.