Update: According to HTC, this problem is currently only affecting the Tegra 3 (international) version of the One X - not the Rogers/AT&T One X or international One XL. HTC advises those affected to contact customer support, though the channel through which you purchased your device is a good bet as well, especially if it was from a carrier or brick and mortar store where they can exchange the unit immediately.
After months of wondering and looking around for answers, we think we've finally found out why all of Verizon's 4G LTE phones (and modems / USB dongles) are having data connectivity issues, and it's a wee-bit technical even for us, but we'll do our best. This information has been gathered from various comments and forums across the net, so, take us at our word here.
When Verizon launched its LTE network in November of 2010, it was the first time the carrier had utilized a GSM-based (WCDMA, as opposed to CDMA2000) network in the United States.