What do you mean deleted, avast doesn't take autonomous action, but alerts and asks the user what action to take. Presumably you chose delete ?
GData also uses avast as one of its two scanners, so effectively one detection and most likely an FP.
Send a copy of the sample (with any personal data stripped out) to virus@avast.com zipped and password protected with the password in email body, a link to this topic might help and false positive in the subject.
Or you can also add the file to the User Files (File, Add) section of the avast chest (if it isn't already in the chest) where it can do no harm and send it from there. A copy of the file/s will remain in the original location, so you will need to take further action and can remove/rename that.
Send it from the User Files section of the chest (select the file, right click, email to Alwil Software). It will be uploaded (not actually emailed) to avast when the next avast auto (or manual) update is done.