I got the same/related problem with my RLC-511W.

If there was a power cut or after some days, suddenly the there is nothing in the playback.
Checking the "Speicherung" I see a red exclamation mark and "0 G / 0 G" after formating the card there is "63 G / 63 G" and the recording works fine.

In the last 12 Days I had to reformat every time after replugging the power (still looking for the best place to attach the cam on the wall) and 4 times without obvious reasons.

The problem is afterwards all data is gone. So I have to download twice a day the data to secure the clips.
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