I ordered my Verizon SIMs through a company called Simetry and have used them successfully with the Digi XBee modem (XB3-C-A2). Unfortunately, I have had these modems fail as well, but for unknown reasons. I have a bunch of the LTE Bee modems, but I can’t use them with our Verizon account because of the end-level certification issue. As far as I know, the Dig XB3-C-A2 modem is the only option available that will work with a Verizon data plan.
If you find another option that will work on Verizon please let us know.