Mazda SD Card won't Update via TomTom Home

GregPullen Registered Users Posts: 3
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I'm trying to update the maps for my 7 year old Mazda CX-5 TomTom GPS system via the TomTom Home app, but it won't recognise the SD card. I have reinitialised the card, which is recognised by my iMac computer, but the Home app won't recognise nor update the SD card. What can I do to fix this?