When an ICS file for an Event in Jive is downloaded and opened through a third-party program such as Microsoft Outlook, the images in the ICS file are designed to be loaded as remote embedded content. If the program is not authenticated with Jive (as with Jive for Outlook), the images fail to load due to authentication issues.
This was mitigated in Jive HOP 9.9 with the issue key JVHOPST-51498 (release notes on Worx). The new version no longer includes the image in the ICS files as they cannot be accessed without authentication. Please upgrade to the latest version of Jive to resolve this issue.
For older versions of Jive, the affected users can still authenticate using Jive for Outlook to view the images within Microsoft Outlook. This workaround doesn't work with any other third-party calendar program due to authentication limitations.
After upgrading, the new ICS files that are generated should no longer have any image links. And if you used the workaround for the older versions, the affected users should now successfully be able to view the images.