Alarm in Reminders is not working.

Hello plumpolka.

Thank you for using the Apple Support Communities. I understand that the option to "remind me on time/place" in your iPhone's Reminders app isn't working correctly, as it does not stay on after it's been set. I'm happy to provide you with some direction to resolve this.

Let's start by forcing the Reminders app it to close. Here are the steps:

Force an app to close on your iPhone, iPad, or iPod touch

Next we want to restart your iPhone by pressing and holding the Sleep/Wake button until the red slider appears. Then dragging the slider to turn your iPhone completely off. After the iPhone turns off, press and hold the Sleep/Wake button again until you see the Apple logo.

Lastly, verify if the issue still occurs within the Reminders app.

Have a nice day.

I have the same problem with recurring reminders not reminding. Rebooting the phone works for a while, but then the problem returns. How often should we have to reboot, every few days? This is Apple, not a Windows phone. I don't expect to have to reboot often.