A folder is no longer found though it is still in the Places list. Draging a file (which may also have Japanese characters) to drop in the Places list usually works. I have found a file which I moved has ended up in the right place intact but the name of this mp4 file has, in addition, replaced the name of an unrelated folder so it looks like that folder has been deleted, but it's only renamed.
It's hard to follow what's going on here. Please re-phrase the problem in terms of Steps To Reproduce. See https://community.kde.org/Get_Involved/Bug_Reporting#Steps_to_Reproduce
[solved] I have been having trouble (left) clicking on the file to pick it up (green +) to shift - not stable. Don't know what changed but now there's no problem. However, when there was a problem it seems I was getting the file name and transferring that to the target folder. The target folder then got the name. Close thanks.
Thanks for the info!
FYI The apparent fix - use the mouse (Lenovo model: M-U0025-O) carefully, slowly, double check every time, etc. - is now discarded in favor of a new mouse. Looks like I had a hardware fault, mouse. I guess it was putting in extra key instructions (noise) which were not requested. (@outlook.com not is use)