One of the ways of opening files for editing and checking them back in to Assets is by using Assets Agent: a small application that runs in the background on the same system on which Assets is used.
In certain circumstances, the connection between Assets and Assets Agent can be lost.
This is known to happen in a Web browser in which a tab that is not active anymore is put into sleep mode. As a result, any connections that exist between an application that is running in the tab and other services are lost.
This process is known as 'Background Tab Throttling' or 'Background Timer Throttling'. It is done to prevent background processes from negatively impacting the working of the Web browser and / or the system on which it is used (such as its processing power and battery life).
In the case of using Assets in combination with Assets Agent, the throttling process results in a lost connection between the two. Some of the check-in and check-out functionality will then not be available anymore.
Note: Disabling throttling allows processes and services that run in non-active Web browser tabs to continue running in the background, thereby potentially negatively impacting performance of the browser and / or the system.
For information about disabling throttling, see the following sources: