Had to reopen this as I am having the same problem but the original thread is closed with no solution. They just asked the OP to send in their logs. That is not a solution the rest of us can follow to fix this issue.
I have the Basilisk V3 and it shows up in Synapse but I can’t add it or have it recognized in Chroma Studio. This problem started happening as soon as I was forced to update to Synapse 4. Everything worked in Synapse 3.
