Hey Joannealiceb,
Welcome to Apple Support Communities.
Since updates include fixes, making sure the devices are up-to-date is recommended. Follow the steps below to confirm the iPhone is up-to-date. The steps are also available in this article:Update your iPhone or iPad.
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
Afterwards make sure the HomePod is up-to-date by following the steps below.
1. Make sure that your device is updated to the latest version of iOS, iPadOS, or macOS.
2. Open the Home app.
3. Tap or click the More button 
, then Home Settings 
> Software Update.
4. If there's a new update, select Update. If there isn't a new update, you can select HomePod to turn on automatic updates and get the latest software automatically when it's available. Software Update also tells you if your HomePod is already up to date, and shows you the installed HomePod software.
If you continue to experience the issue, contact Apple Support here: Get Support. They will be able to continue to help towards a resolution.
Take care.
