Not 100% sure if this is a bug. But setting the PeripheralVisionAngleDegrees to 180.0f makes the enemies look in a 360 degrees angle and setting it to 90.0f makes it see in a 180 degrees angle. Pawnsensing however works differently and there 180.0f is actually 180 degrees.
So this code actually equals to a 180 degree-vision-angle (Which is also visible in both simulate and PIE-playtest when clicking on the enemy with the debug options active):
SenseSightConfig->PeripheralVisionAngleDegrees = 90.0f;
Description in the AISense_Config.h
/** How far to the side AI can see,
in degrees. Use
SetPeripheralVisionAngle to change the
value at runtime. */
It doesn’t say that it is doing this per-eye or that this is doubled somehow. Because of this undocumented behavior + it being weird + it being different from pawnsensing makes me believe this is a bug.