If you are running the Ryzen 3 2200G you might be constricted by the amount of PCIe lanes.
This processor has 12 PCIe lanes. 8 of those lanes will be used by your graphics card, so you have 4 remaining lanes.
I think the standard m.2 slot is x2 uses 2 PCIe lanes and the ultra m.2 slot is x4 so it requires 4 PCIe lanes.
I am unsure of why your intel 545s wouldn't run in the ultra slot, might be some bios settings that needs tweaking, a faulty(old) bios revision, or some form of compatability issue. I have had a previous issues with an m.2 SSD not being recognized, but a BIOS update fixed the issue.
If you were to get a 970 EVO running at x4 alongside the Intel SSD running at x2 you will only have 6 lanes remaining, but it should be fine as your graphics card will switch to running at x4 and will doubtedly have any affect on your framerate.
Just make sure that you are running the newest BIOS version and it should work fine, but to be sure i would recommend purchasing it from a retailer with a good return policy.