Tasks intermittently disappear

Steps to reproduce

1. Have a full task list, normal usage
2. Make edits to any number of entries using web browser (Firefox in my case)
3. Wait between five minutes and 24 hours
4. Refresh task list, multiple tasks show blank with just a checkbox (not necessarily the ones which were edited)
5. All blank tasks show a common "last modified" time which does not match the time you last edited any tasks

Expected behavior

Tasks should not be deleting themselves or disappearing.

Actual behaviour

While similar to #2490, this current iteration of the issue also shows blank tasks when accessed from another app like Tasks.org suggesting it is not a rendering issue, especially given the common "last modified" time.

Tasks app version

0.16.1

CalDAV-clients used

Tasks.org

Browser

Firefox 131.0

Client operating system

Windows 10

Server operating system

Ubuntu (managed by Hetzner Storage Share)

Web server

None

Database engine version

None

PHP engine version

None

Nextcloud version

Nextcloud Hub 8 (29.0.5)

Updated from an older installed version or fresh install

None

List of activated apps

No response

Nextcloud configuration

No response

Web server error log

No response

Log file

No response

Browser log

No response

Additional info

Managed by Hetzner (Storage Share) which somewhat limits access to troubleshooting.

No source files, tests, logs, or server diagnostics are identified. Start by reproducing the delayed blank-task behavior from the listed web and Tasks.org steps, then compare task data before and after refresh; done means tasks remain intact across both clients and the shared modification time is explained or eliminated.