Well, it looks like my “solution” would be better termed a workaround, as the issue recurs each time I restart my PC. There is definitely an issue with the Razer profile and/or synapse, when it first starts up, that they’ll need to correct.
In the meantime, I’ve found a lasting solution, from the Razer Forum, that involves disabling the XBOX Controller for Windows, via device manager, and following a windows restart, the issue appears to be gone forever. Reassuringly, this solution also seems to leave my real xbox controller unaffected, when i plug it in and as I currently have no plans to use my keyboard as a controller, the solution will do just fine for now.
Thanks for the help.