IFRS 9 Financial Instruments

For a debt instrument to be classified as "Amortized Cost", it is subject to two test, one of which is "the cash flow characteristics test" which states that cash flows must consist payment of both interest & Principal. If this test is failed, then the instrument reverts to the default classification "FVTPL". Question sir, just say for whatever reason, the investee is experiencing some financial difficulties relative to a 5 year debt instrument and this investee is only making payments of principal alone. From the investor's perspective, can this instrument be classified at "Amortized Cost" still? The cash flow test clearly doesn't include "Principal & Interest" but rather principal alone. Please advise sir.