Visual Voicemail Playback Issues – How to Fix Visual Voicemail Playback and Greeting Issues

I have a new iPhone SE running iOS 9.3.1, restored from a backup of my old iPhone 4S. Also I have changed carriers upon getting the new phone to Cricket from AT&T.

When I set up the new iPhone, it installed carrier updates from iTunes and the Phone app let me set up my visual voicemail with the passcode and custom greeting, and I tested it out and the visual voicemail worked.

Now, however, when I go to the Phone app and tap Greeting in the Voicemail tab, it brings up the page that would let me play and record a new greeting, but the only working button is Cancel. All the buttons appear as if they work but they don't respond.

I've tried resetting the Voicemail passcode in the Phone settings, I've tried resetting network settings, I've tried rebooting. The problem remains. What is the solution?

One other note, though I can't tell if this is coincidence or the cause, perhaps you can enlighten me: I wanted to completely wipe my old iPhone so it would be ready for another to set up as their own, but that phone's WiFi doesn't work right, and so in order to get internet access enough to unlock iCloud and do the erase, I took my Cricket sim out, and (with a nano to micro sim adapter that came with my Cricket SIM originally) put it in to the 4S so it could get some 4G internet and authorize the erase. After I put the Cricket sim back in the iPhone SE, I noticed it occasionally lose the LTE connection that I don't recall it doing previously in the last week that I had the new phone. Could be a fluke though. And I don't know if the Voicemail greeting problem was around before because I wasn't checking it and wasn't getting lots of voicemails exactly. Also I tried giving myself a test voicemail and it wouldn't let me play it back, though after some resetting or I don't know what the playback works again. Don't know if that's useful or irrelevant or rambling.

Edit: The bit about my iPhone losing LTE, I think I've narrowed down the problem. I think it's just because Cricket isn't yet using VoLTE and I wasn't testing many phone calls. As it stands though I cannot change the greeting except through calling voicemail directly. This is not a massive problem though I would like to know what could be going on or if I should contact Apple Support since this is a new phone.

Also I kept playing around with it and at one time I did get the Greeting controls to work. And then it stopped working again. Don't know what's up or why that would be caused. Is it possible what I did with the SIM would cause this?