Hello,I will be glad to try and assist you with this,Welcome to Just Answer.
When you lose power steering assist on one side and not the other this is indicating a fault within the rack and pinion steering gear.
If this were a power steering pump,hose,or low on fluid issue then the steering would be hard to turn in either left or right directions.
To correct this concern the rack and pinion steering gear needs replaced,these can cost up to $1500 for the part from a dealer and up to 6 hours labor to install and if you want you could go after market for the part and this can cost quite a bit lower usually around $600.
I believe this is what is failing on this vehicle and is causing this concern here.
I hope this information helped,If you need anything else let me know,If you feel satisfied that I have assisted please click accept as this is how I get paid,positive feedback is appreciated,Thanks Pete.