I also had the same problem with wind/water leak in the BR slide. This is for the vertical slide walls.
Will try to explain my solution-
I had my wife move the slide in/out a few times while I observed the action of the seals. The seal on the "non leaky" side "flipped out" as the slide moved out and "flipped in" as the slide went in. The seal on the on the leaky side stayed "flipped in" when the slide moved in either direction possibly indicating that the slide was not centered in the opening, everything else operated "OK".
My solution was to epoxy a 2x2 inch piece of 1/4 inch Plexiglass with well rounded/polished edges to the slide side wall, about 6 inches from the top and about the same back from the front edge of the slide. This increased the friction on the seal as the slide moved to "flip" the seal in the direction of movement. I did the same on the other side of the slide. Viola no more leak!
2017 GMC Denali 3500 4x4 Duramax
2019 Outdoor RV (ORV) Timber Ridge 24RKS