First layer always separates from the part

Something I noticed from the beginning is, that when I print multi material (no matter what Model Material and what Support material I use) the first model layer always peels off the part. Its not that it sticks too much to the raft, it rather sticks too less to the model. What can cause that? It seems to be some malfunction in the slicer/profile. Anything that can be adjusted to prevent that? Or could it maybe be fixed in the slicer? I guess the M300 dual has the same issue…

That is by the way not only with external materials, but also with Zortrax materials. Its also on all my 4 Inventures, so no defect