I just now noticed an issue, and I'm sure it's been happening for a while, but I can't say when for sure because I haven't noticed it until I was actually trying to get at my SD card.
I have 8 GB internal and 8 GB external, and when I go into my storage settings the phone recognizes that. It says I have 16 GB total. It also recognizes when I remove or insert the SD card. It definitely KNOWS it's there. However, I can't actually GET at it in any way whatsoever. In Storage it tells me to insert an SD card for mounting. In Files it tells me the SD card isn't found. The same thing goes for accessing it when I plug my phone into my computer. A new drive even shows up under My Computer when I plug it in, but that drive is displayed as empty. I'm certain this was not the case in the past. It used to display three new drives when I plugged in my phone. One for the MotoCast install, one for my internal storage, and one for my SD card. MotoCast can't find the SD card either.
I did a bit of searching, but I only found one other person with this problem, and they never got a solution as far as I can tell. This is a huge inconvenience for me because I was going to start putting all of my music on my phone instead of my iPod, and I'm going to need more than just the 8 GB to do that. I can use MotoCast Wireless for now, but I'd really rather have it stored on the phone itself.