Sort Order of related, crosssell and upsell products not saving in product edit pages in backend

[tonybrown85]

Preconditions

1. PHP Version 7.0.19
2. Linux cPanel VPS
3. Magento 2.1.5

Steps to reproduce

1. Add related, crosssell, and upsell product against a product.
2. Change sort order of related, crosssell, and upsell products with ajax drag / drop
3. Save Product
4. Sort order doesn't save

Expected result

1. Sort order should save in the order in which they were dragged / dropped in the system backend on each respective product

Actual result

1. [Screenshot, logs]

As stated above the sort order of all related, crosssell, and upsell products should save against each respective product. The data doesn't save at all as I've ran product csv exports and there isn't any sorting data in those respective columns.

[IlnitskiyArtem]

@tonybrown85, Thanks for reporting this issue.
We've created internal ticket MAGETWO-70186 to address this issue.