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Over time Skyline permission requirements have been changed, I would suggest to upgrade your skyline collector to 2.5 and add the below permissions.
The following role/privileges are required for the account used to add the vCenter Server to the Skyline Collector. These role/privileges are sufficient for both collecting product usage data and transferring support bundles with Skyline Log Assist.
- vCenter Server Read-Only role
- Host profile.View
Also during permission on vCenter please add service account directly instead of assigning permission to the group.
we have got the same user with the same permissions on all 3 VCenters - so this can't be
The Onsite Skyline Collector is able to collect and send all the data... it seems to be an issue on your side...