I’m unclear. Are you saying this was 85% of your training max, or your training max (which you set at 85% of your 1RM)?
Example:
If you can get 400 lbs as your 1RM on DL, you might set your TM at 340 lbs (Jim would say you you set your TM at 85%).
But, if you’re doing a set at 85% of your TM (which you set at 340), your weight would be 85% of this, which would be ~290 lbs.
In either case, your TM is too high. I suspect it must be the former or no way you would have stalled at 1 rep. Another method is just to take a weight you can move for 5 strong reps, and set this as your TM. I usually do 5x531 these days as my strength work. For this, I find about 75-80% of my true 1RM works well. I pick three lifts (OHP, Front squat, Weighted Pull ups) or (Weighted dips, DL, Weighted pull ups) and do them as a circuit with 1:30 - 1:45 between the lifts. I know they’re not the traditional 531 choices, but I tend to use bench and back squat a bit more sparingly at the current time and find weighted dips and front squats to be better options.