ACF Block v3 expanded editor fields disappear when viewport is resized to 782px or below

[arica-lbnl]

Describe the bug
With WordPress 7.1 and ACF PRO 6.8.9, the fields in an ACF Block v3 expanded editor do not display when the browser viewport is 782px wide or below. The modal header remains visible, but .acf-modal-block-form-container becomes empty with a height of 0.

To Reproduce
Steps to reproduce the behavior:

1. Using a classic or block WordPress theme with WordPress 7.1 and ACF PRO 6.8.9, register an ACF Block v3 using either acf_register_block_type() or the block.json method.
2. Open the block editor and add the ACF block.
3. Open the block’s expanded editor.
4. Resize the browser window to 782px wide or below.
5. Observe that the editor fields disappear while the modal header remains visible.
6. Close and reopen the expanded editor and observe that the fields reappear.

Expected behavior
The expanded editor fields should remain visible and functional when the browser viewport is resized to 782px wide or below.

Screenshots or Video

Version Information:

• WordPress 7.1
• ACF Pro 6.8.9
• PHP 8.4
• Chrome 151.0.7922.174 and Firefox 154.0.1
• macOS 15.7.3