This I allready tried. It is an LACP problem between one of the 1920 an the 1950.
I can, or at the moment it is my working solution, connect via single link any of the 2 other 1920 switches with the 1950 and the connection is working. I can ping/reach between a single link connection anything from anywhere. The 2 1920 are also working fine via link aggregation with each other, and also by single link. Only the LACP between one of the two 1920 and the 1950 is not working.