Zabbix version:
7.0.31

Issue summary:
We are unable to create or update trigger expressions on the template "Vumacam: Camera Check".

The error references "Vumacam Milestone Cameras" as a missing or inaccessible host, but this is not a host. It is a template in our environment.

Affected inheritance chain:
Vumacam: Camera Check
  -> linked by template: Vumacam Milestone Cameras
  -> linked to 23,604 hosts

Error:
Incorrect trigger expression. Host "Vumacam Milestone Cameras" does not exist or you have no access to this host.
[zabbix.php:17 → require_once() → ZBase->run() → ZBase->processRequest() → CController->run() → CControllerTriggerUpdate->doAction() → CApiWrapper->__call() → CFrontendApiWrapper->callMethod() → CApiWrapper->callMethod() → CFrontendApiWrapper->callClientMethod() → CLocalApiClient->callMethod() → CTrigger->update() → CTriggerGeneral->inherit() → CTriggerGeneral->updateReal() → CTriggerGeneral->implode_expressions() → CApiService::exception() in include/classes/api/services/CTriggerGeneral.php:2056]

Impact:
We cannot maintain or modify trigger logic on the "Vumacam: Camera Check" template. Any attempt to change trigger expressions or recovery expressions fails. This blocks updates to monitoring logic for the templates/hosts inheriting from this template.

Observed behavior:

• Editing any trigger expression on "Vumacam: Camera Check" fails.
• Editing any recovery expression on "Vumacam: Camera Check" fails.
• Creating a new simple trigger on "Vumacam: Camera Check" also fails.
• The same error occurs in both the Web UI and the Zabbix API.
• The same error occurs while logged in as Super Admin.
• Changing non-expression trigger fields succeeds, including:
    - Description
    - OK event generation
    - Tags
    - Other non-expression metadata
• The linked template "Vumacam Milestone Cameras" can have its own triggers edited directly.
• The issue appears isolated to "Vumacam: Camera Check"; we have not seen it on other templates.

Important facts:

• There is no host named "Vumacam Milestone Cameras".
• "Vumacam Milestone Cameras" is the name of a template.
• "Vumacam Milestone Cameras" is linked to "Vumacam: Camera Check".
• "Vumacam Milestone Cameras" is linked to 23,604 hosts.
• No triggers on "Vumacam: Camera Check" reference "Vumacam Milestone Cameras".
• Export/search of "Vumacam: Camera Check" found no references to "Vumacam Milestone Cameras" in trigger expressions or recovery expressions.
• "Vumacam Milestone Cameras" is referenced in the "Vumacam Milestone Cameras" template itself, as expected.
• These are normal triggers, not trigger prototypes.
• No discovery rule / trigger prototype involvement.
• The issue started after the last Zabbix upgrade.
• We have previously deleted historical/orphaned items, some with related names.

Expected behavior:
Zabbix should allow trigger expression and recovery expression creation/update on the "Vumacam: Camera Check" template.

During inheritance/update processing, Zabbix should treat "Vumacam Milestone Cameras" as the linked child template, not as a missing host.

Actual behavior:
When creating or updating a trigger expression or recovery expression on "Vumacam: Camera Check", Zabbix fails during inheritance processing and reports:

Host "Vumacam Milestone Cameras" does not exist or you have no access to this host.

This happens even though "Vumacam Milestone Cameras" is a template, not a host, and the user is Super Admin.

Reproduction steps:
1. Log in to Zabbix 7.0.31 as Super Admin.
2. Open template "Vumacam: Camera Check".
3. Attempt to create a new simple trigger, or edit the expression/recovery expression of an existing trigger.
4. Save/update the trigger.
5. The update fails with the error shown above.

API reproduction:
The same failure occurs when attempting the trigger update through the Zabbix API. The API returns the same "Incorrect trigger expression. Host "Vumacam Milestone Cameras" does not exist or you have no access to this host" error.

Additional context:
The error path includes:
CTrigger->update()
CTriggerGeneral->inherit()
CTriggerGeneral->updateReal()
CTriggerGeneral->implode_expressions()
CApiService::exception() in include/classes/api/services/CTriggerGeneral.php:2056

This suggests the failure occurs while Zabbix is processing inherited trigger expressions into linked templates/hosts.

Question for Zabbix Support:
Could this be caused by stale inherited trigger/function/expression metadata, orphaned records from previously deleted hosts/items, or a regression in Zabbix 7.0.31 where a linked template name is incorrectly resolved as a host during trigger inheritance?

Please advise what database/API checks are safe to run to identify stale trigger, function, item, or inherited-template records referencing deleted host IDs or incorrectly resolving the linked template as a host.

Attachments/evidence available:

• Screenshot showing template "Vumacam Milestone Cameras" linked to "Vumacam: Camera Check".

• 

• Template export for "Vumacam: Camera Check". Vumacam Camera Check.yaml
• Template export for "Vumacam Milestone Cameras". Vumacam Milestone Cameras.yaml
• API request/response showing the same failure.:

 

{
    "jsonrpc": "2.0",
    "error": {
        "code": -32602,
        "message": "Invalid params.",
        "data": "Incorrect trigger expression. Host \"Vumacam Milestone Cameras\" does not exist or you have no access to this host.",
}