This is a 5.xx issue. I've tried 3 different roms, both cm and aosp based, and I came across the same problem with LTE. If you switch to 3g it works fine, just slow as hell when you're used to 4g. I think this depends a lot on location though because a lot of people swear up and down that they have no issues so I guess YMMV.
Well, I decided to dig into the APN settings (Access Point Names under Mobile Networks), and I saw that Verizon Internet (VZWINTERNET) is chosen, but when I go into those settings, most of the values are not set, like the MMSC, MMS port, and the MCC and MNC are set incorrectly, at least according to some of the settings I've seen. However, when I try to manually change them, the access point disappears completely from the list, and I cannot choose anything. Odd.
Maybe this is a known issue though, so if it is, I apologise. I've never had to mess around with these settings before since I've always got strong LTE out of the box.
Other than this, I love the ROM. Since adding *alarm* to the wakelock blocker, I have amazing battery life, and everything else is very smooth.