I’m not able to export gifs with transparency in 126.96.36.199 if the file has a Background layer which is not included in the export (i.e. if it’s hidden or if layers not including the background layer are selected for export). The areas that should be transparent end up glitchy instead. If the background is deleted or changed into a regular layer, the export works fine.
This is what I get, clearly glitchy:
This is what I expect: