No LTE in some ROMs

Hello. My issue is that my phone won't connect to LTE in stock ROM, but it connects with CM 12.1. But my main "concern" is that it used to connect to LTE using stock ROM... To make the long story short: when I bought the phone, it only connected to H, even if I selected LTE in Preferred Network Type (selecting LTE there even made, and still makes my data connection unstable, getting disconnected and rapidly connecting to data network, but only uses H network type) so I selected 3G, because it was made my connection stable.

Then, after some time, I decided to try and select LTE again, and it connected to LTE! Good, fast, stable connection. But after some weeks, I had to wipe my data partition, and again... it would't grab LTE. Some days ago, I flashed CM ROM, and I was surprised that it grabbed LTE with it again. And today, I decided to flash stock ROM again because CM gave me some problems with moto apps (I had to wipe data because it entered in a bootloop), and again, no LTE in stock ROM.

My question is, what can be causing this behavior? I didn't do anything to purposely fix data connection and use LTE, and my phone is capable of connecting to my carrier LTE band (i tested the speed when I was on LTE and yes, it was a lot faster than H), so it should be some ROM/software related issue. I tried to reset APN setting, connecting to the 2 APN that my phone has, and still won't get LTE.

Any ideas of what could be causing this behavior? Thanks!