Not sure if it’s really a bug but when you add an array variable of let’s say a bool and add some default values; then when you change it’s type to actor you can’t assing default values anymore but the old defaults stay.
Default values of array variable are not deleted when changing it's type
Take a look at this thread:
You can change it to an Object to assign the variables within the Blueprint. Alternatively, if you do use Actor as the variable, when you place the Blueprint into a level (if you’ve set the Actor variable to editiable) you can then assign your variables from the Details panel.