I see this in the release notes which seems like the issue in question:
PR 2292798: Virtual machines with Microsoft Windows 10 version 1809 might start slowly or stop responding during the start phase if they are running on a VMFS6 datastore
If a virtual machine is with Windows 10 version 1809, has snapshots, and runs on a VMFS6 datastore, the virtual machine might either start slowly or stop responding during the start phase.
This issue is resolved in this release.