As per the VMware Update Manager Database reset Knowledge Base Article, it is expected behaviour for custom download settings, manually imported patches and ISOs to be removed: Resetting VMware Update Manager Database
You may see below error also in vLCM UI for the affected custom images after the VUM DB reset:
vCenter Server 7.0
vCenter Server 8.0
This is expected behaviour
Please make note of the custom configurations set in update manager prior to running the VUM DB reset
Please ensure you have the custom ISO/addons available for reupload after the VUM DB reset to avoid Images becoming invalid
If the custom ISOs/Patches addons are lost, you will need to complete one of the below options:
1. Download the custom ISOs from your Broadcom Customer Portal and upload to update manager again, see following for steps on this: Download ESXi patches and ISOs for latest releases
2. If it is not available here any longer, please engage with your hardware vendor for the required ISOs/Patches/Addons for upload to update manager