Active speaker enrollment job limit exceeded when batch enrolling AWS Connect VoiceID

I am enrolling speakers into connect & Voice ID using the batch method. Unless I allow the enrollment to be fully complete before starting another I get a "Active speaker enrollment job limit exceeded." error message returned on the 2nd enrollment. In service quotas under connect the only quota I see that would appear to be relevant is Rate of CreateUser API requests. The default says 2 per second, but we are nowhere near that rate and getting the error. Is this the correct service quota that needs to be modified, could there be another cause for the error message, we are definitely no exceeding the default rate. TIA