Here is what I did. I run Mac also, and have done this with 64gb and 256gb sdcard.
I used disc utility to delete all files including hidden files. Then formatted with same utility to format to fat32. And both work perfectly. I did not format to NTFS, because the head unit categorizes better with fat32.
I used Samsung pro 64gb sdcard, and Pny 256gb. I have been using for 6 months now and no problems.
I have read, copy all your music, pictures or video once and leave it alone. If you delete and copy numerous times, you stand a chance of file corruption.
FYI, sdcards up to 32gb use fat32, larger cards use exfat, exfat is Microsoft and they charge companies to read exfat. Pioneer will not pay MS, and therefore, will only support fat32.