Hello Harada-san,
The red text means that an error was skipped while you archived these clips. The most common case is this:
1. You have some partially rendered media on a clip
2. You archive the clip
>>> The software warns you that some frames are missing, but you elect to continue (Silent Mode will do this automatically for you)
3. You restore the archive and the clips that reported errors are displayed with a red text
>>> This is something new that we have introduced in the 2018.3 Update release. There is also a log file showing all the errors generated during the archiving process.
What you can do to eliminate the red text is to open the clip and render any Timeline FX on it or to cache the media. If that doesn't fix the problem, you should contact the support team.
Please accept this as a solution if you feel your question has been answered.
fred
Frédéric Warren
User Experience Designer