After using the DJI Go 4 App I cannot access the video feed via the Mobile SDK from a Mavic 2 Pro without either power cycling the drone/remote or disconnecting and reconnecting the remote's usb cable from my iOS device.
This issue seems to be unique to the Mavic 2 (Pro). The issue does not happen with a Mavic Pro or a Phantom 4. I have tried resetting the DJICamera, DJIVideoFeed, DJIVideoFeedView and DJIVideoPreviewer(DJI Widget) instances but I cannot get the live video feed back. Has anyone experienced a similar issue?
UPDATE: Turns out that changing the aspect ratio, i.e. calling setPhotoAspectRatio:withCompletion and passing it a different aspect ratio than the one currently set fixes the issue. Is there something else that may have the same effect rather than hackily toggling the aspect ratio?
After looking more closely at the DJI SDK Video Preview Adapter code here I realised I was not extending the DJIVideoPreviewerFrameControlDelegate methods parseDecodingAssistInfoWithBuffer, isNeedFitFrameWidth, syncDecoderStatus, decodingDidSucceedWithTimestamp and decodingDidFail which handle video decoding issues. Once I implemented the video adapter I was able to access the video feed regardless of which app had accessed it previously.