Steps to reproduce:

1. Add SNMPv3 interface to host
2. Configure item which uses this interface 
3. Use test button and set Privacy name, Authentication and Privacy passphrase
4. If using a proxy, make sure it has sufficient access to the host
5. "Get value and test" or "Get value"

Result:
See screenshot in attachments. Test fails and returns the message "Timeout while waiting for result."

Expected:
The value for the requested OID should be shown in the value field.

Note:
If the item is configured correctly it still collects data, even though it's not possible collect it via an item test.