2015 LEXUS IS Steering Problems

The steering system on my Lexus IS 350 F Sport malfunctioned while driving at high speeds on the highway. Specifically, the steering wheel locked up and would not allow me to turn, which made it extremely difficult and dangerous to control the vehicle. The car is available for inspection upon request. My safety and the safety of others on the highway were seriously endangered. When the steering locked up, I was unable to make necessary lane changes or navigate slight curves. I had to reduce my speed significantly and move into the shoulder lane as safely as possible. If I had needed to avoid an obstacle or make a quick turn, I would not have been able to. At this time, the issue has not yet been reproduced or officially confirmed by a dealer or mechanic, but I plan to bring it in for a diagnostic inspection. The problem occurred...

When driving at high speeds on the highway (75-85mph) after about 20 mins or so, the steering wheel feels like it locks up or gets stuck. The only way to get it back to normal is to jerk the wheel a bit resulting in swerving. This happens almost everytime I travel across the state. The car has passed all inspections at the Lexus Dealer. This past visit to the dealership, the tie rod was found to be corroded, however the technician does not believe that is the issue. We believe it is the steering rack. This car has not been in any major accidents and was having this safety issue prior to a slight fender bender. The issue is a huge safety concern because the steering wheel "stops respondings" and needs to be jerked or swerved to go back to normal.