This issue is not reproducible. If experiencing this behavior, please reach out to Esri Support Services, as a new reproduction case is needed to continue the investigation.
解决办法
Clear the app cache.
Navigate to the attachment link for the affected feature service. (Example: https:/<hostname.domain.com>/<portalwebadaptor>/rest/services/Hosted/<testfeatureservice>/FeatureServer/<layer id>/<ObjectID>/attachments/<ObjectID>).