I have now tried two MKR SD shields on two MKR1000 boards and none of them will initialize the SD card that works fine on an Uno+Ethernet. Using the CardInfo sample with various versions of the SD library fail to work on the MKR SD shield. Uno works fine. The card is 8Gb SanDisk SDHC with FAT32.
I tried using the SDFat library directly and added diagnostic prints and it seems like some of the commands (CMD0, CMD8) work, but even CMD41 (to determine SDHC) returns different results on the MKR1000/SD (bad) vs. the Uno+Ethernet shield (good). The readCID fails - it just keeps getting 0xFF data back from the card.
I am using IDE 1.8.1.
Has anyone been able to get an MKR1000+SD workinging using the current library and IDE?