just for the record .... I used a Sandisk SD card using the exact same process as opposed to a cheaper SD card that I have been using before and it worked like a charm !!
Steps taken to install (might be relevant for other users):
1. Format SD to FAT using MAC's Disk Utility
2. Extract LibreELEC image to SD card using LibreELEC USB-SD Creator
3. Insert SD card in RP and boot
4. LibreELEC will resize the partition accordingly on first boot
thanks for your help guys !!
Mark