Steps to reproduce:
Precondition: server / agent is running

1. Open Data collection -> Host -> Items -> Create item
2. Select Item type, that has the Timeout option, for example Zabbix agent
3. Add valid item key
4. Select Timeout -> Override
5. Add invalid value as the Timeout, for example type in "test"
6. Switch back to Timeout -> Global
7. Click the Test button
8. Click Get Value and Test button

Result:
The override timeout value is used during testing and "Unsupported timeout value error message" is displayed.
See video:

Expected:
The timeout option, that is selected, should be used for testing the item.