This might be the same problem that PrimoCache has with backup utilities. Acronis, Macrium Reflect and similar bypass the Windows disk drivers, and also bypass the VeloSSD driver. While backing up, the read buffer (SSD) quickly fills up and any attempt by the cache to throw out older blocks from the SSD cache causes synchronization issues. Possibly because the backup utility is keeping the disk volume locked. Or, possibly, because the backup utility is rewriting file timestamps via its own drivers. What exactly happens is a mystery and needs further investigation. Either you get filesystem corruption or you get a corrupt backup, which you discover only after having restored it. That's because most backup utilities cannot detect this kind of corruption.
PrimoCache can be temporarily disabled by pushing a button before backing up. Since VeloSSD has no such option, your only choice is to remove the cache and recreate it later. I have created a small Windows partition. Booted from this extra partition, I create a backup of the main (now offline) Windows partition. This seems the only way of making a guaranteed good backup without causing corruption.
Do not expect backup utilities and disk caches to work together. By nature, they can't. Unless caches become smart enough to know that blocks read by [one in a set of known backup utilities] shouldn't be cached. And even this solution is not failsafe. Because VeloSSD simply has no way of knowing that other programs are messing with the disk via their own sneaky stealthy disk drivers.