Rekordbox Grid Slide mapping with REV5 (bug)

I would like to map the "GridSlide" function of rekordbox with the DDJ-REV5 (currently unmapped) with the combination of shift plus the external part of the jog wheel (like the DDJ1000 and the FLX10).

I go to midi settings > deck tab > add > grid >GridSlide

In the new row (deck 1, type "button") I push "learn" and then in the controller I push shift and I start to move the external part of the jog wheel. Midi In and Midi Out learn the value "B026".

I quit the midi settings and try the new command but nothing happens. Instead, if I move the upper part of the jog wheel (without pushing shift), the grid slides but I can't scratch anymore!