I am not from Intel but The symptom you describe usually means that the memory module is the wrong "density" for the NUC which typically means number of chips per side of the module, for example the NUC may prefer 4GB modules with 4 chips on each side (not 8 chips on each side). Although the model number you provided is usually reported to be good for NUC, the tested memory has an additional number such as .C8FER. Apparently Crucial made some die change and those modules are C8FND which are reported as not compatible in this thread NUC5i3RYH RAM issue - dual module configuration fails to boot
Thanks for your answer really useful. I hope Intel through update NUC‘s BIOS solve the issue ASAP.