By default, the streams "met", "com" and "fac" are not available for EPOC Flex. It is because Cortex doesn't implement the detections (performance metrics, mental command, facial expression) for EPOC Flex.
However, you can configure your EPOC Flex to simulate an EPOC X headset. In that case, Cortex runs the detections that are designed for EPOC X.
All you have to do is to use a sensor mapping that includes all the 14 EEG sensors of an EPOC X headset: AF3, F7, F3, FC5, T7, P7, O1, O2, P8, T8, FC6, F4, F8, AF4.
In addition, you should use P3 and P4 as references CMS and DRL. Please see the EPOC X user manual for the complete EPOC X configuration.
Your mapping can also include sensors that are not present on an EPOC X. Cortex will not use these additional sensors to run the detections, but you can use them to collect more EEG data.
You must configure the EEG sensor mapping of your EPOC Flex when you call the method controlDevice.