Assets and Inventory Plugin comes with Multiple Choice Inventory custom field named "Assets", and it is (by default) added upon installation. More than one asset custom fields can be added to any screens.
Please do not forget to add this custom field to your screens which you want to link assets.
All defined assets are automatically seen under Assets custom field. Just type a few letter and link asset(s) with the issue as below.
Asset Issue Links tab of the asset displays all related issues.