Installing fresh macOS High Sierra on SSD (Crucial MX500) on iMac 2011 21.5 (A1311) (Mid-2011) For reference, I previously successfully installed a SSD (WD BLUE) on my MBP Pro 2011 with no issues, but for the life of me I can't get it to work on my iMac (A1311, mid 2011).

SSD: Crucial MX500 (I chose this drive over OWC as it was slightly cheaper and came with 5 year warranty vs 3 year with OWC).

These are the steps I did:


Attached the SSD via USB2 to SATA to initialize the drive
On a separate USB drive, created a bootable USB High Sierra Installer
Removed Apple OEM HDD, installed SSD with thermal sensor
Booted in Option mode (pressing the Option button only)
Selected the USB drive which had the installer


I can't select the SSD to install.

I can install macOS on the SSD using a USB connection and boot from there without any problems.

I tried installing the SSD internally with and without the thermal sensor to ensure it wasn't faulty, it appears to be a non-issue.

Any ideas?
I exchanged the SSD drive, and it worked!  

For the issue wasn't the installer, it was the SSD itself. I hear that that OWC brand of SSD are less prone to issues. I actually, but the OWC, but then MX500 can on sale and the warranty is longer and the specs are better...but I had to exchange the drive once.