Samsung Galaxy S9+ Verizon based Volte problem

I have always been able to use data while I'm on a call but ever since I purchased a Verizon based s9+ from a third party my 4g lte icon changed to 1x when I'm on a call and I'm unable to use any apps or access the internet. I've tried every APN straight talk has and she with roughly 15 customer service reps trying to fix the issue to no avail. I previously had a Verizon based Galaxy s8+ and simultaneous data and voice worked fine but now on my s9+ my voice connection only connects to 1x causing me to not be able to use any apps at all during calls. Anyone else having this issue?