Odds are they (or someone) has set their privacy settings to hide that. I wouldn't' go changing it unless you've asked them and they want their address to be displayed.
You might also check how your calling is entered in MLS. I assume you are a membership clerk to be able to change it. In which case I'd expect you to see the hidden addresses. If you're not a clerk or bishopric member, then that probably explains it.
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