UE ENDC capable dont connect//establish split bearer to 5G NSA network

5G NR
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1

Hi experts

I have several compatible ENDC handsets and they are compatible with the combination of 4g+5g frequencies used by the operator. Also these UEs detect good 4G-5G coverage.
What other factors can prevent the UE from not connecting to the 5g nsa network? Or in other words, if I am under 4G and 5G coverage what prevents to start or establish the split bearer??

The vendor is ericsson.

Thanks!