Today I installed a Samsung 970 Evo 1TB on my 13" mid 2014 MacBook Pro. I used an adapter that is not the small sintech one that everyone else seems to be using but is a different sintech similar one with a full length pcb.
Once I went into the system recovery mode (Command + R), and went into Disk Utility to detect and recover my backup onto the new SSD, but it didn't show up.
Things I have tried:
Moving SSD around in adapter.
Moving the adapter around.
Adjusting both connections.
Using the Apple provided screw and different combinations of pressure.
I might be, but hopefully didn't, mess up the adapter choice or installed it wrong, but I just want to fix soon to dual boot since I only have 128 GB.