I have the m8 h/k and I don't have any problems at all, now are you rooted? If yes that can be your problem, I got my phone unlocked and s-off and I'm not seeing any problem so far [emoji3]
I have been working today in areas with zero sprint signal and what I have to do to use wifi calling is type my account address , if I use the locate me , it keep telling me "invalid address"
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