Update November 25:
VMware released a fix here.
VMware is getting notorious for bugs in vSphere Changed Block Tracking CBT). Mid November 2015 a new serious bug was found in CBT resulting inconsistent incremental virtual machine backups.
This is a known issue affecting ESXi 6.0 and ESXi 6.0 Update 1. Currently, there is no resolution.
The knowledgebase article of VMware is here.
A workaroud for Veeam B&R and Trilead is described here.
The workaroud for Commvault is described here.