You can get it to work by doing the following, which is enabling Advanced Calling.
Settings > Cellular > Enable LTE > Select Voice & Data. Once this is enabled the hotspot will work while on a call. e.g. voice and data at the same time.
Here is an FAQ on Advanced Calling 1.0 for Apple devices that VZW offers: http://www.verizonwireless.com/support/apple-advanced-calling-faqs/
Hope this helps.. let us know.