Virtual Machines being migrated using HCX fails at "Collecting source details" under Events section on the source side of the migration.
VMware HCX
This indicates an issue with the HCX manager being unable to communicate with the virtual machine guest operating system (OS). This is commonly caused by storage related issues that may impact the virtual machine's hard disks or VMware Tool's operational state.
Perform the following steps in order:
1. Reboot the virtual machine.
2. Storage vMotion the virtual machine to another datastore.
3. Investigate the underlying storage that the virtual machine resides on.
If the above steps do not resolve this issue, please collect the below information when filing a support request with Broadcom:
Source side HCX log bundle, including IX appliance.
Source side vCenter log bundle
Source side ESXi cluster log bundles
virtual machine names
HCX migration ID
Timestamp of migration(in UTC)
Reference this KB article and any troubleshooting steps performed.
Compute vMotions may still be successful within the same vSphere datacenter.