Unlocked s10 from Walmart not compatible with xfinity mobile?

After months of research and speaking with an Xfinity Mobile representative, I purchased a Samsung S10 unlocked @walmart. I was assured it would work with my service. The phone works great! Except my Xfinity voicemail isn't working. I get no notification of voicemail. There are none showing in the app. I can however call my # & retrieve voicemail. I chatted with an xfinity mobile representative yesterday. After a lengthy conversation he told me this phone is not compatible and I will continue to have problems with it. Xfinity still shows my previous s7. Then asked if I wanted to register it. Should I try to return this phone to Walmart? It's full paid for. Thank you, Frustrated.