Automation saves timestamp in wrong format in yaml (Sunset/sunrise offset not triggering)

Hi everyone,

this is my first post here.
I have a problem with the automation of a sunset/sunrise trigger where the automation won’t get triggered.
I searched around in this forum and found a solution here
The problem ist that when I save the automation in the frontend it saves the time offset for the sunrise/sunset not as string but in the format:

offset: -00:30:00

Then the automation will not be triggered.
When I correct the value directly in the yaml to

offset: '-00:30:00'

then it will be triggered.

The Problem is that everytime I edit any of my automations in the frontend gui it saves the offset in the wrong format.
Am I doing something wrong here?

Thanks in advance

Marco