Sounds like The specified item was not found.
And.. well... I can add that my response in that thread... well, it was from an iPhone.
Maybe it has something to do with iDevices? There was a post recently something about iPhones hijacking MMS.
It seems like it's an apple problem because I get other texts just fine but it seems like Apple is only telling folks to delete and then re-add their android-using friends. Oddly enough I was getting texts regularly until today.
I'm having the same issue, but it is specifically when I'm connected to wifi. I am missing mms messages (group texts from iphone and android users across carriers) as well as phone calls periodically. The problem seems to be well documented on google and t-mobile forums and has something to do with how the Nexus 5 is routing the MMS because it doesn't have wifi calling capabilities. I'm getting very frustrated as I'm connected to wifi 80% of my day and t-mobile continues to suggest that I file a warranty claim through the manufacturer.
Here is something to try:
Go into Hangouts, then Settings, then SMS.
Click 'Access point names.' By default, mine was set to 'MetroPCS,' I changed it to 'T-Mobile GPRS,' try that or another.
Another possible solution here: Solution to Picture/Group MMS on WiFi
There was a known issue around the time of this post: I had the same issue.