While renaming files, if you copy paste to the old name field and empty out the new name field and hit enter, nothing happens (other than the window closing). Just figured out what was happening today.
If you delete unwanted items in the old name field, rename functions properly.
The New Name field is where you put the new name you want the file to have. If you empty that, the rename isn't going to do anything.
The Old Name field lets you use wildcards to do renames which work on multiple filenames at once. If you just want to type a new name, you shouldn't edit the Old Name field at all, and just type the name you want into the New Name field.
I'm sure that would normally be the case. However, I edit part of the filename...it has extra stuff that I no longer need after processing the file. I delete the new name section because I don't want the stuff that is in old name any longer. Works like a charm. However, you can not copy/paste into the old name field and expect it to function properly. It just does nothing to rename the files.
I could create a small video file for you??
Here is a video of what I'm doing. When you see me highlight the text, that is so that I can use it on other files that has the same info that I no longer need. You'll see DOpus works great and renames it. But, if you paste the copied information into the old name field and clear the new name field and hit okay...it doesn't work like I just showed you.
I can't load the video. Can anyone else?
I can.
I can too and I don't see any problem.
All of your file names end up with 720x480 10.
You're in find and replace mode, in Find you have 720x480 10 and in Replace you have nothing (an empty string).
The preview of the result is exactly what you're asking: all of your filenames have been striped from the string 720x480 10.
Or maybe I am missing something ...
EDIT: Tested it on a bunch of files here, and the removed part is actually removed when pressing Enter. Maybe you should have made the video longer (in time) and larger (in pixels) so we can see you hit the OK button (identical to Enter) and see the content of the folder after that.
I don't see anything wrong in the video either. It's doing exactly what it's told: Finding 720x480 10 in the filenames and removing it (replacing it with nothing).
I can see your point. Let me process some more files tonight...and I'll get a complete video in 1920x1080. Should make it easier to see. I will also use buttons instead of enter.
Okay, here's a new video. I figured out what I was doing to cause the issue. I was selecting files from different directories. Then I would just use ctrl-v and paste in the info that I didn't want in the old name and then blanking the new name. It doesn't work across directories. Not only that, but if you deselect the file that is the other directory and try to find/replace again, it still won't work. This was done in 1920x1080. Should be much easier on the eyes. 
There's nothing wrong with selecting from multiple folders.
The issue here is that all the files you selected end up with H.265-1920x1080-10 and you're trying to replace H.265-720x480-10.
The string you're trying to match does not exist in the selected filenames ... so it's doing nothing as expected.
holy... ok... I feel stupid now.
Thanks for pointing that out.