Go to Settings > Apps > click the three dots on the top right > select show system apps > after system apps appear, search for "Smart Call" > Click on "Storage" > Clear data and cache.
Good as new. At least mine was.
I tried this first with just clearing the cache and that doesnt work.
Don't know if you have to do both but you definitely have to clear the data.
Pretty disgusted by Samsung on this though for their lack of testing. This is a basic phone feature. Tge one area of a device that should be considered sacred. The device MUST work for calls. Imagine needing emergency service for someone with breathing difficulties justbe be told you can't make a call because of a software update. Basic stuff Samsung. Basic!