The combination PC-0.4 and PVA-0.8 wouldn't print because the raft was getting so big that it intersected with the prime tower. Moving the prime tower 1mm down allows us to print again.
Relax warning constraints for top and bottom thickness
With very thick layers, fewer layers will still provide enough strength to not sag. 2 is quite a hard minimum though because there are 2 different orientations.
The 3mm was computed from wanting 7 lines, but in that calculation I used a line width of 0.4mm. This is obviously wrong, since for 0.8mm profiles the line width is 0.8mm.