Tracking of Uranus with RxB and the fives method was performed for about 100minutes between HST 02:58 and 04:25. Uranus moved from (az,el) = (120,46) to (148,57) passing through azimuths 125 and 141 at elevations of approx 43 and 53, respectively. At these azimuths the race defect reveals itself. An empirical correction based on the 1997 profile was used with an amplitude at the horizon of 3.0". The tracking residuals are plotted as a function of azimuth below:

The defect is essentially not detected at az=141, although the azimuth tracking noise between az=139 & 142 sems to have increased, while the defect appears to be largely uncorrected at az=125, although increased elevation pointing noise at about the same time casts some doubt upon that too.

The next test should be taken with the correction disabled to try to establish the profile afresh.