Ensure what the format of the AssignedTo0.Email looks like. It probably won't be as simple as "Bob.White@domain.net". It'll probably have special characters, claims, and other junk that you'll have to figure out how to navigate around.
For debugging, I write things to a variable, such that I can see what it's assigned, prior to sticking it into the impossible-to-debug Actions like "Filter Array". (I don't know why Microsoft hates developers so much nowadays.)
In all of my Flows, I initialize a variable called strCodeComment, and I use it to write out values, take notes, etc, such that when debugging, I can see stuff at a glance within the Run instance.