I had problems unarchiving a vast collection of 114 sequential .zips (the final .app is +11GB...) so I resurrected The Unarchiver from the Trash to see if it might help. It didn't but it reminded me why I had trashed it in the first place: it is unable to handle such large files. It has been running for thelast 2+ hours, saying 'Preparing to extract <filename>'. A search for a part of <filename> via Easy Search' - set to find all files and folders, to ignore case and to search invisible etc. locations - finds nothing new to indicate that it is even writing anything to a file anywhere. Stuffit Expander took a fair while (many minutes) but completed, if not successfully.
Any suggestions why it should not go back into Trash?