nRF5340 QSPI operation with errata 171 workaround set to run at 96MHz seems to operate at 2.5MHz

I have applied the errata 171 workaround to a zephyr code base with an MX25 chip and set the speed to 96MHz - when I run the application (engineering D silicon) with a scope on the QSPI clock line, I see a 2.5MHz clock. If I then change to 48MHz operation and use the alternative workaround for errata 171, I see a 42MHz clock pulse. Is it not possible to get 96MHz QSPI working on this silicon revision?