[H] Fast Boot Failure

[didymus7]

My present system, based on an Asus ROG Maximus X Hero, had been booting 
fine with 'fast boot' for almost two years.  Last week, fast boot would 
boot me directly to the UEFI BIOS and unless I selected 'Save and 
Reset', it would continue to boot right to BIOS.  Of course, the 
solution was to switch off Fast Boot, but I was wondering if anyone knew 
what changed to cause fast boot not to work.  Anyone know anything about 
this?

Thanks...Steve