MMS messages have stopped working for me in the last few months. Zero changes my end.
Used to work perfectly fine, then some days, pictures took ages to send, upwards of 5-6 minutes. Also had a day trip in Auckland and I couldn't send any. As soon as I landed back in Christchurch, they worked.
Now, they won't send or receive at all. I get the text to say I've received a MMS message etc but they don't download (Have wifi off etc).
Device is a Galaxy Note 8 but I'm pretty much 100% sure it's Sparks end not mine as I've made zero changes my end and they used to work, I've confirmed the MMS APN settings and have also re-installed the configuration message you receive when joining Spark.
Zero issues with anything else, just MMS.