This particular Anime has a semicolon ‘;’ in it’s Title, which caused issues with numerous applications and plugins.
It properly detects the files, but can not rename them as it can’t find the files according to the log.
Trakt link: https://trakt.tv/show/steinsgate
Renamer wants: http://d.pr/i/vwyx
Log output: http://d.pr/i/cEIb
Suggestion: Make a exception and replace it by a . or space 
The issue is the semi-colon in the folder name, that is somehow causing the file not to be found on disk (as shown in the error message). As soon as I change the folder name and remove the semi-colon, change the path in drone and rescan it renames it without issue (and includes the semi-colon in the file name), I’m also able to rename to another format from the file that contains the semi-colon.
You’ll just need to follow the same steps to resolve it.
Yeah had to rename the folder, the filenames where no problem