Download button missing for non-admins when multiple assets are selected

In AEM6.1 SP1 or SP2, when you select multiple assets in the /assets.html Touch UI interface, download option is missing in Card and List Views, however, it shows in Column View.

Cause

It is a product bug fixed in AEM6.1 SP2-CFP3.

Resolution

Apply AEM 6.1 Service Pack 2 and Cumulative Fix Pack 3 or later from here:
https://helpx.adobe.com/experience-manager/kb/aem61-available-hotfixes.html