Must click "Update" twice to save values to post_meta

UPDATE 2:

Properly triggering a change event on the input also solves the issue. DO NOT trigger an event on a jQuery selector of the input (like I tried a million ways).

let field = acf.getField('field_123456');

// trigger change event on $input()
field.$input().trigger('change');

---

UPDATE:

Works fine if I set a value attribute on the input element. Plain javascript because jQuery's prop() and attr() didn't seem to work.

let field = acf.getField('field_123456');
field.val('some value');

// add value attribute to input
document.querySelector('.acf-field[data-key="field_123456"] .acf-input-wrap input').setAttribute('value', 'some_value');

I'd still love to understand the original issue. Maybe some sort of "dirty" status that's not set when using ACF val() but is set when editing the field manually?

---

Describe the bug

Wondering if anyone has any insight on a custom ACF block issue? ("blockVersion": 3, "usePostMeta": "true"): values set in block with javascript are not saved to Db unless Update is clicked twice.

Within wp-admin, editing a post:

1. I set a field value via javascript while a block is being edited:

let field = acf.getField('field_123456');
field.val('some value');

3. I see the value in the text input on-screen
4. I click "Update" for the post, but value is not written to dB. ***
5. I click "Update" a second time, and value IS written to the database.

*** If I manually place the cursor in any field in the block and add/delete a character, THEN values are saved the first time I click "Update"

Sure seems like ACF triggers some event/condition when there's a manual edit, but NOT when the value is changed via the ACF JS API.

What is that event/condition? I've had no luck figuring it out...

To Reproduce
See above

Expected behavior
When I click Update the first time to save the post, the values set via the ACF JS API are saved to the db.

Version Information:

• WordPress Version [6.9.1]
• PHP Version [e.g 8.5]
• ACF Version [e.g ACF PRO 6.7.0.2]
• Browser [all of them...]

Additional context
I've submitted a ticket, and searched the forum but did not find this issue.

Start by reproducing the block update flow with acf.getField(), field.val(), and field.$input().trigger('change') in the issue’s example. Inspect how the ACF JavaScript API handles value changes and confirm that the first Update persists the value to post_meta without a manual edit.