Assuming that the system is stabilizable and controllable, if the Bat algorithm works well for other optimization problems, then most likely your adaptive controller (AC) design structure is causing the instability that results in a singularity at around 30.2 seconds.
It could be an issue that your AC is adapting to the changes in the system either too fast or too slow, leading to some destabilizing parts of the system's dynamics are not adequately compensated for.
Without proper constraints, the Bat algorithm is probably unable to tell this, and keeps on searching in some directions that tune the AC parameters, causing them to diverge, and resulting in the instability.
