I added this as a comment yesterday instead of as an answer.
We had issues with this very issue. That is a Samsung S10e calling a Moto Z4 and the person on the S10e not being able to hear the Moto Z4.
I found that System Update 14 has a fix for this. This update did not update automatically for the 4 phones that we fix with this update yesterday. They had to manually go in and check for the update.
Update notes for System Update14
* Includes performance improvements that increase the stability of your phone.
* Addresses a one-way audio call issue on specific devices.
***Go to Settings, System updates, Check for Updates.***
System update 14 has a fix for this.
Hope this helps