This apparently happens only when you paste AND copy and can easily be reproduced:
- Launch SVN Log
- Paste some text in the message filter bar (doesn't really matter which text)
- Clear the message filter, or modify it so that you see some results in the revisions list below
- Select a couple of revisions, right click and select Copy to Clipboard >> Revisions (Here it doesn't really matter what exactly is being copied)
Result: There will be nothing in the clipboard, i.e. when you try to paste, it will appear as empty. Any further attempt to copy-paste something afterwards will silently fail.
Now when you open a powershell prompt and enter
"hello" | out-clipboard
You will experience a timeout and an error message saying:
out-clipboard : "Requested Clipboard operation did not succeed. Clipboard owner: TortoiseProc.exe:3608",
When you close the SVN Log window you will get your clipboard back.