Hey there gbol,
Thanks for reaching out to the Apple Support Communities. To get started, when you say that the hub is working fine in the Hue app, are you able to see that your accessories are powered on and control them as expected?
If so, and if Bluetooth is enabled on your iPhone, we'd recommend restarting both your Wi-Fi router and modem (if separate). This can help with resetting the connection between your iPhone and the accessories and may be able to help with resolving the issue.
If still having issues after restarting your modem and router, the next best option would be to remove the accessories from the Home app, and set them up again; however, this may require you to restore the accessories to factory settings. If that's the case, you may need to reach out the Hue's support, visit their website, or check the Phillips Hue Bulbs manual for help with these steps.
Let us know if that's able to help.
Have a great day!