Apple normally addresses charging issues that arise following a large iOS upgrade rollout with minor firmware
updates that include the appropriate remedy patch. Check for available
software updates on your iPhone to install if you haven't previously.
Go to Settings-> General-> Software Update to do so. If an update is available, you'll get a notification with information on the new firmware.
If there is, back up your iPhone data first, then follow the onscreen instructions to download and install the update.