Importing Kotatsu backups not working properly

[NonSnameX]

Brief summary

when I try importing a Kotatsu backup zip, most of the data from it does not load into Futon, whether it be the library history, updates and also favorites. weirdly enough when I try to backup Futon and check its files, I can see that the files are nearly same in size compared to the Kotatsu ones. (I don't have a JSON viewer or editor on my phone, but taking a quick look using MiXplorer's Code Editor I can see that the contents of " history" in both backups are pretty similar).
I wonder if there's a specific formatting difference that I'm not noticing.

Steps to reproduce

• On Kotatsu:

1. Go to Settings.
2. Tab on "Backup and restore".
3. Tab on "Create data backup".

• On Futon:

1. Go to Settings.
2. Tab on "Backup and restore".
3. Tab on "Restore from backup".

Afterwards, you can create a backup for Futon and then compare both the Kotatsu and Futon backups.

Futon version

9.6.14 - Latest stable version at the time of writng this issue.

Android version

8.1.0

Device

Probably (and hopefully) not relevant, but : Y5 Prime - DRA-LX2

Acknowledgements

• This is not a duplicate of an existing issue. Please look through the list of open issues before creating a new one.
• This is not an issue with a specific manga source. Otherwise, you have to proceed from parsers repository.

[LandWarderer2772]

That's strange. I dont know what's causing that

[NonSnameX]

I attached both of their respective backup zips here if you would like to try it out. (Warning: mostly NSFW stuff)

futon_20260424-2317.bk.zip

kotatsu_20260424-2255.bk.zip

[NonSnameX]

interestingly, they work properly on both Kotatsu Redo and Kotatsu Next. I wonder why.
(it technically also works on Usagi but that app is still a work in progress).

[LandWarderer2772]

if they work on those then it should work here