If the logging problem started after installing a flow sensor, then I suspect the issue is that there is too much log data that exceeded the flash memory space allocated to data storage (which is 1MB by default). If you have a way to roughly estimate how much there there is on an average day, please let me know so we can figure out how much data is accumulated. We will probably have to implement a way to erase old log data when too much is accumulated. Of course there is also the possibility that the SPIFFS (flash) library has a bug causing this, which we can investigate further.