Hi Richard, sorry I'm just seeing this now. Yes printks seems to have some parsing issues. I think decimal points within the string can upset the rest of the string. In this case, you need to insert spaces instead of the tabs that aren't being read properly. Sorry, not a solution, just a workaround.
fprintks doesn't seem to append properly if the file is opened and ciosed, as is happening here. If it is just a single instance of the opcode running continuously it should work. However, if you simply want to write played notes to a score file I would use fprints instead. So in instr 10 you could put:
if release:k()==1 then
event "i", 11, 0, 0, iStart, kDur, iNote, iVel
and instr 11 would look like:
fprints "scor.orc", "i %2.0f\t%15.6f\t%15.6f\t%d\t%d\n", p1, p4, p5, p6, p7
Note that in order for the start times to be produced in this instrument, the record button must first be clicked.