Office app does not show Collabora template previews unless hasPreview is set

[truAlexeyRu]

Describe the bug
After upgrading to Nextcloud 34, the Office app shows Collabora document templates, but all template cards display only the generic document icon instead of preview images.

The preview URLs are generated and Collabora preview images are reachable, but the Office UI does not render them unless hasPreview is explicitly set to true in CollaboraTemplateProvider.

To Reproduce

1. Use Nextcloud 34 with richdocuments 11.0.0 and office 1.0.0.
2. Configure an external Collabora Online server.
3. Open the Office app.
4. Look at the template cards such as Syllabus, Resume, Letter, Invoice, etc.
5. All cards show generic icons instead of template preview images.

Expected behavior
Template cards should display their preview images.

Screenshots
Attached.

Client details:

• OS: Windows 11
• Browser: Chrome
• Version: 149
• Device: desktop

Server details

Operating system:
Docker deployment on ASUSTOR ADM v5

Web server:
nginx reverse proxy

Database:
MariaDB 11

PHP version:
PHP from official Nextcloud Docker image

Nextcloud version:
34.0.0.12

Version of the richdocuments app
11.0.0

Version of Collabora Online
26.04.1.4

Configuration of the richdocuments app
{
"apps": {
"richdocuments": {
"disable_certificate_verification": "",
"doc_format": "ooxml",
"edit_groups": "",
"enabled": "yes",
"installed_version": "11.0.0",
"public_wopi_url": "https://collabora.example.com/",
"types": "filesystem,prevent_group_restriction",
"use_groups": "",
"wopi_allowlist": "172.18.0.0/16",
"wopi_callback_url": "https://cloud.example.com/",
"wopi_url": "https://collabora.example.com/"
}
}
}

[elzody]

Would you be able to share some screenshots, browser console logs, or browser network logs? Although I am experiencing some unexpected behavior (not displaying templates in OpenDocument formats), I have not experienced the previews not loading, so it will require further debugging.

At this point, I'm not sure if it's related to https://github.com/nextcloud/office or this repo, so the issue will stay here for now until we figure out where the problem lies.