eCommerce stock and price management changes not visible in admin.

Prerequisites: Install Ibexa Commerce on postgresql.

Steps:

1. Create a product (with or without variants).
2. Go to eCommerce tab.
3. Enter changes in Stock management.
4. Save.
5. Enter changes in Price management.
6. Save.
7. Reload the page.

Actual result: Changes are not visible.
Expected result: Changes are stored and visible in admin.

Remarks: Stock and price changes are visible on frontend.