Can't find group when attempt to import group from Azure AD

Today when we attempt to use the "Import Users Group" funtion from Azure AD to define different policies for control with this process.
Import user groups from connected apps in Defender for Cloud Apps - Microsoft Defender for Cloud Apps | Microsoft Learn
However, we found some strange phenomenon : There will be part of groups that can't not be found in the search result.
And seems that we can not find a clear pattern about what caused that.

The target group was synced from Active Directory to Azure AD, but there are also other groups also sync from AD can be found in the search result.

Does anyone have any idea about this ? Thanks in advance.