I've been having issues on my Galaxy S5 running Android 5.0 where I either don't receive an MMS, or I receive a notification but can't read the message.
Here is an example where I can't download the message. Tapping the "Touch to download" text doesn't do anything:

In the other case, a friend showed me a group MMS where both of us were on the thread, but I never received anything on my phone. This doesn't happen with every MMS, but it's happened about 5 times this past week and I can't find any commonalities -- some group MMS's work, some with photo attachments work, but sometimes the message just never goes through.
Any ideas on how to troubleshoot this?
Thanks,
Zach