First, did you try deleting and reinstalling Reflect from a fresh download?
Second, you may have an additional problem besides Reflect; M.Reflect will not create read errors from your hard drive. If you are, indeed, getting read errors that is coming from your drive, not Macrium Reflect. You may want to check out your main drive and your backup drive as well.
You can use Seatools for Windows for this. Run the short test first, and if it finds bad sectors, run the long test. If you have a Toshiba drive, use Gsmart Control.
The easiest way to backup your system is to create a system image. Very easy. The Reflect screen appears complated, but that is because MR offers many different options for certain situations; you can ignore most of them. I know you already described the procedure that gives you problems, but here is it again anyway just in case I am missing something.
> Click the Reflect shortcut on your desktop, Reflect opens.
> Reflect has regular updates, be sure to always update if it offers to.
> If you haven't yet, make an emergency restore disk. You will definitely need this in the event of a partition corruption, or a mechanical failure of some kind that prevents the computer from booting. You can make this by choosing "Other Tasks / Create Rescue Media at the top left headers.
> Have your backup drive connected. In the screen, place a check mark on ONLY System Reserved and your main Windows partitions; no others. Your backup drive may be showing, but do not put a check on it (obviously).
> Under Backup Tasks (left menu on the screen) click on Image Selected Disks on this Computer.
> In the Disk Image screen, under the Destination header, Folder should be enabled; make sure that the drive letter there is the same as your backup drive.
> Still in the Disk Image screen, deselect (clear) the checkbox Use Image ID as File Name
> Underneath it in the text box, type in the current date. I use all caps, for example: FEBRUARY_8_2018. If you should need to perform a restore in the future, this makes it very clear and easy to understand which file you will choose to restore if you have several going back several months, like I do.
> Click Finish, lower right of screen.
> In the Backup Save Options box, Enter A Name For This Backup, enter current date.
> Click OK and the backup starts.
> In the active backup screen is the option to shut down the computer on completion. You can start the backup before retiring for the night and it will be done in the AM with the computer shut down.