I use File History as *part* of my home back-up regime and have found it quite reliable. However, I have noticed that it has failed to restart its regular back-ups following both the upgrade to 1803 and more recently 1809.
The failure is silent (no error messages) and File History appears to be turned on when you look on its main page. It is only when you dig deeper under “more options” that you find that the last back-up is prior to the feature update.
I have seen this on 3 devices – all HP laptops. Two back-up to a network location, one to a USB connected hard drive. In all cases the back-up locations are accessible via File Explorer so it does not seem to be a connectivity issue.
The fix I have found is simple. Just clicking the “Back Up Now” button under “more options” wakes File History from its comatose state and all is well until the next feature update.
I’m just posting this observation in case it is applicable to others. Perhaps some people think they have a working back-up when they do not!