Hello Leigh and welcome to the community,
This is an interesting issue. I have not seen this. This might be better for customer care to look at. I would recommend your admin open a case with with customer care Routing team. I don't know if they will find anything right out of the gate but they can dig in more technically than we can do here in a public forum.
I would recommend providing interaction id, screen shots of whats being sent and whats being received, make and model of the iPhone as well as current OS. I believe this would be enough to have care start investigating.
Cheers,
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Cameron
Online Community Manager/Moderator
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