iM 4,1-14,4 SSD will only work as an external drive

[eoghan!]

I have an iMac 12,1 with upgraded i7 CPU and AMD Polaris 4GB GPU 20GB ram.
The problem I have is that my King Spec 1TB 2.5" drive will not work internally only in an external usb enclosure.
I have a Samsung 860 Evo 500GB that will work both internally and externally.
The !TB drive was in my mac mini 6,1, but the 500G was at one time too.
Has anybody else had a problem like this?
I'm afraid to do a clean install as all my data is on the drive (I have a time machine backup drive tho')
Any help appreciated

 

[MacInTO]

I had some issues work a Corsair SSD and certain MacBooks. Here is the thread, https://forums.macrumors.com/threads/corsair-force-le-ssd-incompatible-in-some-mbp-models.1988942/

It turned out to be an incompatibility with the SATA controller and a chipset on the motherboard. Your issue could be similar.