Previewing the Rename Glyphs filter is broken (in the info window as well as the main window) in version 1038 and 1043. It still worked in v 1037.
Btw, the preview of spacing changes like Transformations;LSB:-4.0;RSB:-4.0; is wrong if I also change the UPM for that instance, looks as if it was applied before the UPM change. That’s an old bug, though.