[v5] Inconsistent File Visibility in Files Field After Upload in Kirby 5.0.0-alpha.4

[jirichlebus]

Description

In Kirby 5.0.0-alpha.4, uploading files using the Files field does not behave consistently. The upload process completes successfully, but the uploaded file does not always appear in the panel immediately after the upload. This functionality worked correctly in Kirby 5.0.0-alpha.3.

In some cases, the file appears in the Files field as expected, while in others it does not. Refreshing the panel always resolves the issue, and the file becomes visible and can be saved correctly. Without refreshing, the Files field sometimes remains empty, making it seem as if the upload failed.

Testing multiple Files fields within different blueprints may help reproduce the bug and understand its inconsistent behavior.

Expected behavior
After uploading a file in the Files field, the file should consistently appear in the panel immediately, as it did in version 5.0.0-alpha.3.

To reproduce

1. Use Kirby 5.0.0-alpha.4.
2. Create a blueprint with one or more Files fields.
3. Upload a file using the Files field in the panel.
4. Observe that the file does not consistently appear in the field after the upload.
5. Refresh the panel, and note that any missing file becomes visible in the Files field.

Setup

5.0.0-alpha.4 (issue)
5.0.0-alpha.3 (working as expected)

Console output
Not tested.

Your system (please complete the following information)
Device: MacBook Air
OS: macOS Monterey 12.5.1
Browser: Chrome
Version: 130

Additional context
This issue affects a project that worked perfectly in Kirby 5.0.0-alpha.3 with an identical setup. In alpha.4, the file upload succeeds on the backend but is not always reflected in the panel without refreshing. Testing multiple Files fields across different blueprints may help reproduce the inconsistent behavior and better understand the scope of the bug.