Here's an example [B1134.2] where TSARH missiles engage without illumination.
In this case, an SU-27 has fired AA-10s at some allied fighters. The missiles are flying on autopilot until terminal illumination is required.
However, the Su-27 is destroyed before its missiles reach the target.
The missile gets no further updates, and proceeds on a straight line course and passes astern of its target, passing over 1.2 km behind the target. Without terminal illumination it is not able to home in on the fighter.
However, the program resolves an engagement anyway, which can result in the destruction of the target.
The expected behaviour would be for the missile to fly on without engaging until it is removed due to fuel exhaustion.
I have also seen this behaviour when TSARH missiles complete engagements although the attacking plane has been forced to turn away so its illumination arc should no longer cover the target. (Specifically the illumination arc, not the narrower white arc of the radar.)
(Series of examples attached.)
