Something doesn't make sense here. With your numbers (and I assumed a CYA of 30 ppm, though that doesn't make that much of a difference), 4 boxes of 20 Mule Team Borax (each 76 ounces weight) would raise the pH from 7.2 to 8.65 in your 11,000 gallon pool. It would also increase your Borates level by 24 ppm.

If I initially assume you already had 50 ppm Borates in the pool, then the pH rise would be less, but still to 8.2. Get some AquaChek Borate test strips and test your Borates level. Maybe it's really high, though that would only reduce the amount of pH rise from adding more Borax but shouldn't stop it completely.

Borates won't show up very much in the TA, but they act as a pH buffer, especially against having the pH rise, but the amount you are seeing is very strange.

Richard