The title pretty much sums it up. Create any combination of Radial Filters, Graduated Filters or Adjustment Brushes on your image. Make the image B&W (V). Toggle the B&W Adjustments off and you lose all of your adjustments.
REPRO: - launch LR Classic - D to edit an image - add any combination of Radial Filters (shift+M), Graduated Filters (M) or Adjustment Brushes (K). Just one will suffice. - V to convert to B&W (starting in B&W has the same effect) - turn off the B&W adjustments (this is the HSL tab if the image is in color)
RESULT: All adjustments are gone. Poof! EXPECT: All adjustments to remain in place.