Yes. This is what we have been saying the whole time -- That is the issue... it is bugged and it will not drop down to HSPA for the call therefore you wouldn't be able to make calls at all. To 911, your mom, your gf, etc. -- No one and since you couldn't that means it would violate laws and T-Mobile isn't going to do that and get fined (hence why they care).
I have read around that there will eventually be a VoLTE update for us on T-Mobile which means Motorola and T-Mobile will have to be working together to get the phone VoLTE Certified for T-Mobile.
And it won't look for a non-T-Mobile GSM or HSPA connection because it sees that T-Mobile is available on Band 12.