no, I do not impose a stationary condition on the periodic boundary. As it can be seen from the images above, these faces are defined as "Deforming" in the Dynamic Mesh settings. Unfortunately I still have not gotten the remeshing to work in the meantime. The remeshing inputs for length scales etc. seem to be okay, because as mentioned above the remeshing is working perfectly fine with these values as soon as I leave out the periodic boundaries.