I got the new editor to add items yesterday, mainly just the stuff needed for the Poppi QT Pi quests. There was no confirmation of saving, but when I re-opened the save, all the changes were there. Game loaded the save fine, but it completed all of my quests or reset them. The quest log was completely empty. I was like whatever, Ill just work on the story some more. I do the next story quest in Leftheria and go to save. It said there was not enough space left, delete some data, and appeared to save anyways. I exited the game and checked the device storage, about 32 GB free on the sd card and half the system memory left. I go back into the game and Just get New Game and Settings options. Tried to start new game and save it and same thing happened with the error and save disappearing on game start up. A backed up "clean" save also encountered the same thing. So I went into Save Data Management in the Switch settings and deleted all save data for the game and powered off the Nintendo switch. I then turned it back on and the new fresh game I started was able to save and load properly. I was then able to edit it with the older editor and added Tachyon chips, legendary cores, money , ether, and bonus xp for Nia, Rex, and Tora.
RealSpyKitty, you can use this one here. It's working fine with the new DLC installed. Core Chip id and serial numbers are on the very first post under old editor. Just make sure you have some in your inventory to overwrite. If you don't, it will corrupt the save or does nothing all if your lucky.