What was the file name, location and malware name of the detection ?

You shouldn’t be right clicking on the file but using the drop-down list in the Action column for that detection.

Using the “Apply this action for all.” if you choose the “Move to Chest” option that is selected for all of the detections in the list. So when you click Apply it will send all of the detections to the chest. The reason the Apply button is then greyed out is because the actions have been carried out and can’t be repeated as you are effectively viewing historical information in the scan report.

There is nothing to stop you from physically checking in the avast chest to see if it is there. avastUI > Maintenance > Virus chest.

Perhaps this could have been placed in the viruses and worms forum, but it isn’t clear cut as you aren’t asking about the detection as such, but more the interface.