I have a feeling this is an issue with the Action 5 Pro too.  If you use the Pre-Rec feature the Mic 2 will time out and cut off making you lose all audio on the future recording.  I use the Pre-Rec feature to watch my fishing rods and it can take up to an hour for a fish to hit my bait.  Which means not only I do not have audio I have no way to manually refresh the Mic 2 as I wait.  This is a pretty big issue for me.  
This also impacts the remote to a lesser extent.  I hit record once and it shows me the seconds of pre-record.  I have to hit it a second time to continue the record.  If the remote is not timed out all I have to do is click record once.  Its an annoyance.  I got the remote so I would not have to use my phone to start a recording.  If I am using my phone I have to click the Action 4 record button and that click is audible on the recording.

As a side note, Pre-Rec still can not be enabled using a cellphone.  Its an ability I've asked for since the Action 3 was granted the Pre-Rec feature.  Which is the best feature of the camera!

Does DJI even care about Pre-Rec issues?  Two years and its not added to Mimo and now this problem with the DJI Mic 2.