Text messages disappear between phone restart and phone unlock

Scenario: my phone restarts (either after being turned off or running out of battery) and opens to the lock screen. While still locked, I receive one or more text messages, which display as notifications on the lock screen. (The notifications display their senders' phone numbers rather than their names, presumably because the phone can't pull contact information until I've unlocked after restart??)

I touch the home button to unlock the phone. As this is the first unlock after restart, I receive the message "Touch ID requires your password when iPhone restarts." I enter my passcode and my phone unlocks.

My notifications pulldown does not show the new text messages. My Messages app does not have a badge showing any notifications. If I open the specific contacts within Messages who sent me the texts (assuming I was able to recognize the phone number!), the most recent message is from our last conversation, not from today. All trace of the text messages I received while my phone was locked have simply vanished.

This has occurred for both SMS messages and iMessages—though if they were iMessages, I can typically view them on my iPad or MacBook Air without issue. It's possible that this has occurred for other notifications besides text messages as well (missed calls? voicemails?) though I haven't specifically noticed.

I have noticed this problem for all or nearly all (not sure) of the messages I have received while my phone was locked after restart, for at least several months. Is this a known issue? Any suggestions?

Phone: iPhone SE, iOS 11.4.1

Carrier: Verizon 32.0