Did the last Giants update, 1.21 break anything? The windrows now look really funky, and balers won't pick up the windrows. I have tested base game maps and balers, and this does not happen.
Viewing post in FS25 Judith Plains, Montana 4X comments
I just started a new save this morning on Judith Plains. Mowed some grass into windrows, then ran a baler over the windrow. It worked perfectly, so not sure if your issue was related to something else. But like I said, I had this exact same issue on Iowa Plains View for both grass and straw swaths that were laid down prior to the patch.