Huge amount of files deleted despite being "moved to the virus chest"

[Ng9]

They cannot be found in their respective folders nor in the virus chest. Is this because the virus chest was "full"?

I transferred a folder filled with false positives from my external hdd to my internal hdd, after hundreds of pop up notifications. Only about 50 can be found and restored from the virus chest. The other files were shown to have "moved to the virus chest" as well but I can't find them in the virus chest. How can I recover these files?

[DavidR]

There are factors that effect what action is taken on detections.
We can't say if it was because the virus chest was full as we don't know what size it is set for or the total size of the files being sent.

Can you give an example of some of the files detected, file type, etc. ?
I say this as some files archive files could fail on a move to the virus chest. 

Did you make any changes to the default file shield settings, Actions ?
I say this as that is one of the settings if the action fails Delete.

I wonder why you felt it necessary to move/transfer them from an external drive to an internal drive, that action is certain to have avast scan newly created files (as this transfer would be classed).  Copy would certainly have been safer as your file would remain in the external drive.