Hi @Mel_Rooney, welcome to the forums! I’m Francisco from Zwift Support.
Thanks bring up this to the table!
A key point to note is that major iOS updates often reset app permissions to their default (more restrictive) settings, which can affect the functionality of the Zwift Companion app as Paul and colleagues mentioned.
This means you might need to manually grant permissions for Wi-Fi and Bluetooth again.
To fix this, please head over to this Apple support page and make sure that Location Services is enabled for Zwift Companion. Wi-Fi and Bluetooth permissions are bundled under Location Services, and this is what the Companion app needs to function properly.
After the iOS 18 update, you’ll likely find these permissions disabled, so go ahead and adjust them. Let us know if enabling these permissions solves your issue!
Check this other thread in our forum for references. Another clues here.