Bug of saving in the background of Illustrator 2020
If you save a document that uses a 2-byte spot color name in ai format, place this file in InDesign, Illustrator, etc.
It will be replaced by "Global color". And even if you export the PDF, it will be reflected. Turning off saving in the background can work around this, but this is an issue that should be resolved as soon as possible.

I am happy to share that we have fixed this bug in our latest release – 24.1.1 for Win and 24.1 for Mac which is available worldwide now.
Going forward, our goal is to fix as many top User-Voice bugs as possible and as frequently as possible. Given the nature of the fixes, some of the bugs will take a longer time to fix, but we are on it.
You can update to the latest release using Creative Cloud desktop App: https://helpx.adobe.com/in/creative-cloud/help/creative-cloud-updates.html
Thank you for all the feedback. Keep it coming!
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Micah Kayden Gael commented
It's possible that you are encountering a bug with saving in the background in Adobe Illustrator 2020. Some common causes of this issue include:
Insufficient memory: If your system does not have enough memory to handle the saving process, it can cause the background saving to fail.
Slow hard drive: If your hard drive is slow or full, it can also cause the background saving to fail.
Corrupted preferences file: The Illustrator preferences file may become corrupt, causing saving problems.
Network issues: If you are saving the file to a network drive, network issues can cause the saving process to fail.
To resolve this issue, you can try the following steps:
Free up memory: Close any unused applications and clear the cache to free up memory.
Optimize hard drive: Defragment your hard drive and clear out any unnecessary files to improve performance.
Reset Illustrator preferences: Reset the Illustrator preferences file to resolve any corruption issues.
Check network connection: Ensure that your network connection is stable and functioning properly.
If these steps do not resolve the issue, you can try uninstalling and reinstalling Illustrator or contacting Adobe Support for further assistance.
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monokano commented
This bug is very serious because it affects all non-ASCII language users. Should be fixed immediately.
Japanese:
このバグは非ASCII言語のユーザー全てに影響するので、非常に深刻です。即刻修正されるべきです。 -
monokano commented
v24.0.0-24.0.2
If non-ASCII characters are included in the spot color switch name, the color name is automatically changed to "Global color" on the PDF side of the Illustrator file. This occurs when background save is turned on. Does not occur if background save is turned off. This is probably a bug in the background save function.Japanese translation:
v24.0.0-24.0.2
特色スォッチ名に非ASCII文字が含まれていると、IllustratorファイルのPDF側でカラー名が勝手に「Global color」に変えられてしまいます。これはバックグラウンド保存をONにしていると発生します。バックグラウンド保存がOFFなら発生しません。バックグラウンド保存機能の不具合でしょう。