Exchange coupled double layers based on rare earth- transition metal ferrimagnets have been shown to have very large exchange bias. The fields needed for their saturation can easily exceed several Teslas. Understanding how these systems revert microscopically, is a crucial step toward employing these systems for high field devices of micron size and below. We use vacuum non-contact MFM to obtain quantitative measures of the stray fields at different applied fields, from 0 to 7 Teslas. The reversal of the ferromagnetic layer coupled to the ferrimagnet is unusual, in that the high Zeeman energy domains revert through the formation of isolated reversing regions comprising a high energy interfacial, in-plane domain walls. The onset of these reversing regions can be controlled by reducing the interlayer coupling.