Automations not working on my iPhone 15 Plus after updating to iOS 18.4

It's not always the iOS update's fault!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

Group Text/Chat messages on iPhone can come in various formats and types, each with its features and purposes (Which one you are referring to is not clear here):

1. Apple Platform (iPhone, iPad, and Mac)
   1. iMessage is Apple's proprietary messaging service, available only between Apple devices. iMessages are sent over Wi-Fi or cellular data rather than traditional SMS networks. iMessage offers enhanced features such as read receipts, typing indicators, multimedia support (photos, videos, etc.), and end-to-end encryption for privacy. These messages appear in blue bubbles in the Messages app.
2. Group message: There are three types of group messages that you might see: group iMessage, group MMS, and group SMS. The Messages app automatically chooses the type of group message to send based on settings, network connection, and carrier plan. For example:
   1. If you and your recipients are using Apple devices and iMessage is turned on, then the group message is sent as an iMessage. If you can't turn on or sign in to iMessage or FaceTime - Apple ... If you can't turn on or sign in to iMessage or FaceTime - Apple ...
   2. If you send a group message to people who are on Android, then the message is sent as an MMS or SMS message. Check if you have an SMS plan enabled by your carrier for the SIM/eSIM that you use on your device. Apple Inc. does not provide SMS services. You need to contact your Carrier to enable SMS and/or MMS.
3. Carrier (Cellular Service Provider)
   1. SMS (Short Message Service): SMS is the traditional text message format used on all mobile phones. It is limited to 160 characters and is sent over the cellular network. SMS does not require an internet connection, but it also lacks features like media sharing or real-time typing indicators. Messages sent via SMS appear in green bubbles on an iPhone.
   2. MMS (Multimedia Messaging Service): MMS allows users to send multimedia content, like images, videos, and audio, along with text messages. Unlike SMS, MMS requires a data connection. MMS messages also appear in green bubbles on iPhones, as they are sent over the cellular network instead of Apple's iMessage system.
   3. RCS (Rich Communication Services): RCS is a modern messaging protocol designed to replace SMS and MMS, offering features similar to iMessage, such as high-quality media sharing, read receipts, typing indicators, and more. It is supported by some Android phones and mobile carriers, though not yet universally available. RCS can be used in messaging apps that support it, but it is not natively integrated into Apple's Messages app at the moment.
4. Third-Party Text Messaging Apps: In addition to iMessage, iPhone users can install and use various third-party messaging apps such as WhatsApp, Facebook Messenger, Telegram, Signal, and more. These apps typically use internet connections (Wi-Fi or data) to send messages and offer additional features like voice and video calls, group chats, file sharing, and security features (like end-to-end encryption). These messages are usually separate from iMessages and are managed within their app.

Each of these types of messages may have different behaviors, settings, and limitations depending on the network, device, or app being used.