I think I cleaned well after the glue and cement mortar dried, but it still sticks because the sealant shrunk.
The seam on the floor on the floor, height 1 cm, depth 0.5 cm, a cord vilaterm behind the sealant. The seam broke not because of the settlement of the plate, but the sealant itself dried out and broke off at the weak point.
Get a normal sealant, Mapei or Tytan.
Try treating the area with acetone before applying the sealant.