Gerrymandering is an issue. Please see https://www.govtrack.us/congress/members/map, and zoom in on Austin.
Austin is a part of the following Congressional districts: TX-21, TX-25, TX-31, TX-17, TX-10, & TX-35. Of these districts, only one (TX-35) is Democratic.
On the other hand, Lamar Smith (TX-21) is one of the Representatives for the Bluest city in the state.