THUNDERBOLT DISPLAY TO MOJAVE NOT POWERING UP ---- SOLUTION
I had the problem with instability when I upgrade the thunderbolt display to Mojave, sometimes its was black screen, I tried some solutions as: restarting TD and it powered up and sometimes didn't , doing reset for everything on mac and display without success. Tried also change the cables, once again not good.
SOLUTION
GO TO SYTEM PREFERENCES --- DISPLAYS ----- COLOR AND CHANGE THE SCALE FORM THE DEFAULT TO ONE BELOW IT.