This issue is occurring on tons of iPhones for last several months. Apple does not bother. After the initial template response on the thread, they haven't even acknowledged the issue despite the fact it is reported by several hundred users.

Apple does not raise defect reports from the support site.

You need to raise a report on Radar. I think you can now create a free dev account and get access.

For an iMessage problem I had Apple engineers call me and debug the issue by remotely taking over control of the iPhone.

Omg this thread helped me solve it. It never crossed my mind that customizing the per app/in app sharing options would cause this and I trimmed my sharing options down and the problem went away! PHEW!

You may want to wait for some time to check if it reoccurs. Several users reported initially that it fixed the problem but later realized it was only a momentary fix.