Some suggestions:
Pull the membrane out again, and inspect the two rubber o-rings at the downstream end of the membrane. Make sure they are in good shape.

Can you give us some detail as to how you are measuring your tds levels? We've had more than one occurrence where tds readngs were being taken in a less than clean container and causing erroneous readings.

You're only getting a 71% rejection rate out of your membrane so that is the place to start looking for the problem. Your membrane is passing "dirty" water to your DI and exhausting it quickly. You DI is now passing water with 67 ppm tds - the resin is exhausted.

When was the last time you replaced your carbon block?