I have tested with a known-good other SD card (the previous one was brand new, out of the packet) and I cannot get a true return from SD.begin(...). Please can anyone help with how to address/debug this? Has anyone else reported their SD card reading failing before?
EDIT: I have read some other instances of people having SD card issues on this forum. Having looked at their issues, I have ensured I have a 16GB (not larger) FAT32 formatted SD card. I have also tried SD.begin(4, SPI, 1000000); and 10 MHz too in M5EPD.cpp but it still returns false. I have also remembered to remove and reinsert the SD card between boot cycles where power has not been removed, so each SD.begin() should be the first that the SD card controller sees. Any other ideas?