Samsung S8 Advance Calling Bugs-- Speaker phone and voicemail issue

[Android Central Question]

I have the oddest issue... my speakerphone often doesn't work well on the S8 plus. I read today that if you turn off "Advance Calling" that the speakerphone will work much better. It worked, my speaker phone issue for months was finally resolved. But with Advance Calling off, now literally every call I received goes straight to voicemail. I turned advance calling back on and, sure enough, I could receive calls again but my speakerphone was back to working poorly. Any advice? I'd really like a useful speakerphone and to be able to receive calls.