First day of the week not consistent, displaying wrong dates

[ylwsub68]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

In calendar view, I have the first day set to 0 (Sunday). The days of the week still show up with Monday first, but the dates in the calendar grid show up as if Sunday was the first day. For December 2024 for example, it shows December 2 as Tuesday, when it is actually Monday. Additionally, when I go back into the options, the "first day of the week" option keeps getting set back to 1 after I set it to 0.

Expected behaviour

Matching dates and days!

Steps To Reproduce

Incorrect calendar shows up on a Chromium browser running on a Raspberry Pi. Shows incorrect sometimes on a Chrome browser on Windows. HA running on a Raspberry Pi.

Mode

Calendar

Card Version

10.0.0

Home Assistant Version

2024.11.1

Configuration

No response

Relevant log output

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

Hello @ylwsub68, thank you for your interest in our work!
If this is a bug report, please provide your configuration and any screenshots that would assist troubleshooting, otherwise we can not help you.

[sampellino]

I am experiencing the same issue. Looks like the value of firstDayOfWeek is being ignored. If I change it, the lovelace card's preview updates correctly, but the calendar within the dashboard does not update.

Before YAML/GUI update:

After YAML/GUI Update: