Stigg said:
Very reliable until Changed Block Tracker (CBT) was implemented. Version 6 was rock solid, but with version 7 came CBT which has caused lost of issues over time. And there is very little to be gained from it.

My advice is when you install it, uncheck "Install CBT". And if you have already installed it, go into Control Panel > Programs and Features (or Settings > Apps), find Macrium Reflect, and right click on it (or click in Apps), and select, "Change" > "Next" > "Modify", and uncheck CBT.
Free version does not use CBT.