Suffering with this problem as well - for users like myself it's truly frustrating and a huge time suck. I have sometimes 100 files in a folder that I have to look at and determine which to delete. I've created a "to be deleted
folder" where I move the file to but it's absolutely insane I should have to do it that way - and it takes me twice the time to do it this way. Such a basic function and they are pretending the problem doesn't exist.
I'm in the same boat. The whole point of previewing is to roughly know what is in the file instead of opening the whole thing, closing, then deleting. If I already know which files to delete by name, I don't need preview at all. The other thing that sucks
is if I accidentally delete a file, the same problem happens with the recycling bin, where restoring that file doesn't work if in the preview pane. Though in that case I'm usually only trying to restore one file and can just turn preview pane off.
Luckily I have System Mechanic as my antivirus and can send the file to the incinerator from the preview pane. But it would be so much better to have the ability to delete instead.