Having some weird trouble with a migrated M2 website. I've seen some resources on here, but they all don't seem to be showing the same symptoms.

Migrated a site using the Magento tool - all went well apart from an odd issue with the select attributes not functioning as expected.

If I update a migrated attribute (Say Attribute Value "A" to Value "B"), it will revert to "A" on save.

However, If I create a new product (non migrated) and do the same thing on the same attribute it updates as expected.

I've read that it may be an issue in the eav_attribute table.

For reference, this is one of the troublesome attributes (which were also migrated):

*************************** 1. row *************************** attribute_id: 595 entity_type_id: 4 attribute_code: type attribute_model: NULL backend_model: NULL backend_type: int backend_table: NULL frontend_model: NULL frontend_input: select frontend_label: Type frontend_class: NULL source_model: Magento\Eav\Model\Entity\Attribute\Source\Table is_required: 0 is_user_defined: 1 default_value: is_unique: 0 note: NULL 

Compare that to a test attribute I created after migration:

*************************** 1. row *************************** attribute_id: 1212 entity_type_id: 4 attribute_code: test_select_attribute attribute_model: NULL backend_model: NULL backend_type: int backend_table: NULL frontend_model: NULL frontend_input: select frontend_label: Test Select Attribute frontend_class: NULL source_model: Magento\Eav\Model\Entity\Attribute\Source\Table is_required: 0 is_user_defined: 1 default_value: is_unique: 0 note: NULL 

There's no difference in the set up, so the backend_model issues I've read about don't seem to apply here.

Other issues I've noticed:

In debug.log, there's a bunch of these errors:

main.WARNING: Attempt to load value of nonexistent EAV attribute '575' for entity type 'Magento\Catalog\Api\Data\CategoryInterface'. [] [] 

Also, I can't for the life of me get these attributes to load in layered navigation. I would assume it's related to the above issues.

Anyone out there who's able to help at all?

Cheers

** EDIT ***

It appears that if that test product (which was saved successfully) appears in the category, Layered Navigation works as expected, so it has to be something to do with the attribute values and not the attribute itself.