Getting these messages:
Facts:
1) It's not blocked by local provider. I can use the same local sim card with non-Verizon phone(international version).
2) Phone LG G4. Android 5.1.
3) I can make calls, internet is working with local GSM provider. I had no problems with tethering in US with Verizon SIM.
Since I travel a lot, when I was purchasing the phone and getting the service, I was assured that I will not have any problems with SIM swaping, since the phone is unlocked. Very weird - you need a enable some Verizon plan, while working with non-Verizon provider.
Spent about 24 hours of my vaction time trying to find out the solution. Called to Verizon tech support. They have no idea. I am very disappointed how all these companies now are doing their jobs only half way, cutting time and money on testing of their products, leaving it to the customers to discover all these issues and resolve them, or not disclosing about these issues, when I sign up for the service and buying the phone.
Please help.
I am sorry to say I cannot help, only empathise.
I live overseas and acquired a phone I like a lot (HTC One Mini 2), but it is ex-Verizon and came with their restrictive overlay/branding. Yes, it works in my country in Global Mode, with a local SIM card, so it was network 'unlocked'. BUT... like you, tethering is blocked as I do not have a Verizon SIM card installed. Also software cannot be updated unless in CDMA mode, which does not exist where I live!
I too wasted a lot of my life trying to work around this, I need tethering when away from home.........
Nowhere to enter an Unlock Code.....
I tried a free Hotspot App called Fox-Fi but I couldn't get it to work for a Wi-Fi hotspot, Verizon have dug deep I think. You may have better luck with other Apps, there are a number claiming to help out.
What else is left, rooting? Not a procedure I really want to try.
I shall probably just drawer away this phone and get one from the local market, where by the way, even Network locking of phones is not permitted! The government makes the laws not phone companies here. 
Please let us know if you get around this, and beware of buying refurbished phones when travelling.
And those who travel overseas for work, you may need to consider this.