I had exactly the same issue with my Kickr snap. Since the snap (in contrast to the core) does not support multiple Bluetooth connections at once, I use ant+ with my computer (using an usb dongle) and connect to my vantage M using Bluetooth. What resolved the issue is to first connect to the watch and afterwards connect to the computer. A friend of mine has a Kickr core and confirmed this solution also works here: first connect to the watch via Bluetooth, later connect to all other devices via Bluetooth (e.g. Wahoo app or to the computer).