Date property time picker forces ISO format instead of respecting user-defined date format

[Wanten]

Steps to reproduce

1. Create a new note and add a date property in the Properties panel.
2. Manually enter a datetime value using a custom format, for example:
   2026-02-01 16:53
3. Open the “Date and time picker” for this property.
4. Select any time from the picker.
5. Observe the resulting value after the picker updates the field.

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Expected result

• The Date property should update the value using the same datetime format already used in the note or property (e.g., YYYY-MM-DD HH:mm).
• The time picker should respect the user’s chosen date format instead of overriding it.

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Actual result

• After selecting a time in the Date and time picker, Obsidian rewrites the value into ISO 8601 format:
  2026-02-01T16:53:00
• This happens even when the existing value uses a different format such as 2026-02-01 16:53.
• The forced ISO format breaks workflows that rely on custom datetime formats.

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Environment

SYSTEM INFO:
	Obsidian version: v1.11.5
	Installer version: v1.11.5
	Operating system: Windows 11 Pro for Workstations 10.0.26200
	Login status: not logged in
	Language: en
	Insider build toggle: off
	Live preview: on
	Base theme: dark
	Community theme: none
	Snippets enabled: 0
	Restricted mode: off
	Plugins installed: 0
	Plugins enabled: 0

[Pch]

I’m not entirely sure (as I’m on Mac) but I don’t think this is necessarily a bug …

I mean, AFAIK and per the FR below, Obsidian saves date and date & time values in Source mode as YYYY-MM-DD and YYYY-MM-DD[T]HH:mm:ss respectively when adding the values through Properties (either manually or using the date/time picker in Live Preview).

Properties: let the user customize the way Dates/Times are saved/written

This FR was created to capture the discussion related to letting the user choose in which format the dates of type “date & time” in properties are saved on file. Currently, we use ISO 8601, extended syntax, second resolution, local time. While the format chosen for the internal representation may be subject to minor changes in the future, we do not plan for having the users pick a different format. We would like to have fixed format to facilitate interoperability with outside software. If you…

The formatted date/time values you see in Properties (in Live Preview/Reading mode) has always been just a display of the saved values in Source mode…

[combs]

I have been running into this when switching a text property to a date property. I have typed a text value in USian format, “2/11/2026” for example, and it garbles it terribly to “11/20/0002” when switching to date property. It is displayed in my ideal format but parsed as something else, presumably ISO given this thread.