Hi,
maybe I found the bug ;)
I have Samsung A8 (2018) Dual SIM with Android Oreo. If somebody call to the second SIM, I can't see Caller ID on watch. But if somebody send SMS to the second SIM I see the name correctly.
I switch to Garmin from Samsung Gear S3 which handle this without any problem and as a bonus (which is very practice) show from which SIM card the notification came.
Do you have the same experience?