You still get that errors not because the isValid node don’t work but because you are recovering data (the boolean variables) from a source that doesn’t exist.
If you follow the execution flow you can notice that the “Check if Blue” loop contains a branch that get variables from other 2 loops that wasn’t running.
My advice is to store your actors arrays into 4 variables and use the get node to retrieve the correct boolean variable.
Something like this
