sometimes a diagnosis item can not be removed with PNS_IF_REMOVE_DIAG_REQ

if a diagnosis item has been added to the stack (e.g. PNS_IF_ADD_CHANNEL_DIAG_REQ) and an alarm has been sent (PNS_IF_SEND_DIAG_ALARM_REQ) which has not yet been handled by the IO Controller and in this situation the diagnosis item shall be removed the removal does not work.
In this case the removal fails with "TLR_E_UNEXPECTED" and the diagnosis item remains set.

This is not a typical usecase for real life as all known IO Controllers confirm diagnosis. However this may happen during certification tests when performing the acyclic tests.

Expected behavior: Diagnosis can be removed at any time.