So, just checked the poll more closely.
"Immigration/illegal aliens" isn't the most important topic. That's a LIE.
It's consistently behind "dissatisfaction with government/poor leadership", almost always by a double digit margin.
Only this month it was ahead (by a whole 3%!), but this is still frankly inaccurate.
Furthermore, depending on how you were compiling data, "situation with Russia" might very well mean "international relationship", and you could easily count people worried.
Or "immigration" might very well account for people, say, appaled by the family separation policy recently enacted.
What is important to note ultimately is that this data serves as a basis for what people would consider to be the "most important problem", but tells us nothing about how they actually feel about it or what their politics are.
You are making wild assumptions based on your politics on what the data could mean; and you're doing a poor job of it too.