Issue with rxr

I have a question on the rxr.c program in regards to Supraventricular Run detection. I have noticed some discrepancies in the results given by bxb and rxr for a few records. For example MIT Record 221 shows no Supraventricular Ectopics, however rxr shows there are 45 Couplets, 166 Short Runs and 103 Long Runs.

Please see below results from comparing the original atr against itself:

Record Nn' Sn' Vn' Fn' On' Ns Ss Vs Fs' Os' Nv Sv Vv Fv' Ov' No' So' Vo' Fo' Q Se Q +P V Se V +P S Se S +P RR err
221 1806 0 0 0 0 0 0 0 0 0 0 0 345 0 0 0 0 0 0 100.00 100.00 100.00 100.00 - - 0.00

(SVE run detection)
Record CTs CFN CTp CFP STs SFN STp SFP LTs LFN LTp LFP CSe C+P SSe S+P LSe L+P
221 45 0 45 0 166 0 166 0 103 0 103 0 100 100 100 100 100 100

I don’t understand why there would be 0 Supraventricular beats yet many Couplets and Runs of Supraventricular ectopy in this scenario. Please let me know if my understanding of these results is off or I am missing something.

Start with rxr.c and reproduce the SVE run-detection output for MIT Record 221, then compare it with the bxb results and the original annotation comparison shown here. Determine whether the discrepancy comes from the reported beat counts or from how couplets and short and long runs are classified; done means explaining the mismatch or identifying a reproducible defect.