Interesting, so B: is part of the M105 output which is typically filtered. I can try to turn off the filtering and see if it helps, but of course best to make the filtering more precise.
One thing I don't get is that having B in the output ( in this case it's reporting results from a probe head calibration) actually causes multiple lines before and after the B to be missing, not just the specific line in question. Would that still indicate it's an M105 filtering issue?
One other issue, while you're looking is that Repetier Host does not seem to allow leading spaces or tabs in the serial output. This makes formatting of report output challenging as one needs to put something to hold the first place in the line like "|" followed by however many spaces/tabs are desired.
