Thanks. Our printer is Ultimaker S5, bought on November 2019. The material is ABS and supporting material is natural PVA.
But it is during the printing process that we encountered the problem: "One material appears to be empty. Please change it to a new material to continue printing." We checked the printer, but two materials are not empty. And if clicked on "OK" and "Resume", the printer continued to print. But the same problem appeared after several minutes' printing.
By the way, we also observed some strange clusters of the supporting materials printed on the structure, which could be seen in the attached images. Is there any way we can solve it?