Certain songs cannot be processed

[rkha3665]

When I tried to get a bpm edit of https://osu.ppy.sh/beatmapsets/874178#osu/1827120 , the program failed to generate a new difficulty. I assume this is because of the metadata, as once I shorted the artist (桐崎千棘 (CV: 東山奈央), 小野寺小咲 (CV: 花澤香菜)) to (kirisaki), the program was able to run successfully.