Can't boot to installed OS on USB stick

[DaedalusOS]

I've got 2 USB sticks, an 8GB one for the installation ISO, and a 128GB one that I have installed Debian onto.

I sat for 30-45 minutes waiting for Debian to finish installing onto the 128GB flash drive, it did successfully, then it booted to it. I had to go to work so I shut everything down and left. When I came back and attempted to boot to the flash drive, it just won't. No GRUB boot loader, nothing failing, it just won't boot to it. I just had Debian dual booted on my SSD until I formatted it to go back to just Windows.

ASUS Motherboard (Maximus VII Formula if you need that part)
i7-4790K

Idk if you need any of that, but any info could help.

I don't understand why I was able to boot to it at one point, but now I'm not able to.

** I've gone to Google, tried searching here, can't find anything that's been helpful.

*** I reinstalled Debian onto the flash drive, I was able to boot to it twice until I unplugged it, booted to Windows, plugged it back in and attempted to boot to it again.

[sunrat]

Can you boot using the Boot Select menu? It's F12 during initial boot screen on mine.

[Horizon_Brave]

When you boot to it initially, when it works, do you use Grub to access the boot partition? I mean to say, does the grub menu actually appear on the screen, before you launch debian? Think it could be a graphical issue? What graphics card is installed?

[debiman]

I was able to boot to it twice until I unplugged it, booted to Windows, plugged it back in and attempted to boot to it again.

maybe windows is interfering.

[stevepusser]

I was able to boot to it twice until I unplugged it, booted to Windows, plugged it back in and attempted to boot to it again.

maybe windows is interfering.

Try removing and replugging the drive without a boot to Windows in between to see if that makes a difference. If it's still OK, try a boot to Windows without it plugged in, if that wasn't the case in your earlier attempts. It might be that Windows is somehow changing the UUID or something if it ever "sees" the drive.