It seems many are having Miitomo photo issues. IF YOU ARE LINKED to a Nintendo Network Account, delete/reinstall seems to fix this issue. WARNING: DO NOT DO THIS IF YOU ARE NOT LINKED, or you will LOSE EVERYTHING. From what I can gather, this may have something to do with the Nintendo Network maintenance, as my network miiverse was wonky too there for a while. (I thought maybe I had gotten banned there for a minute, lol).
Initially, I did have an issue trying to reinstall (freak out moment!), but it seems to all be good now. However, should the issue not be cleared all at once on the network’s end, and people’s clear up at different times, you may have some delay in getting this resolved. I wanted to get word out there, because there doesn’t seem to be much information regarding this issue, let alone any solution to it.
Most other times with any Miitomo issues, simply clearing cache and/or restarting your phone will solve things. I’ve never seen this photo problem though, & it seems to be going around.
*Note* This will fix the issue with your own Miifotos, you still won’t be able to view others’ photos posted until their own network issues are resolved.
-This has been a Miitomo public service announcement from Mistress J-