It certainly was badly broken at one point / for a while... I looked at fare basis that the cert was pulling and it was obvious that it was looking for specific fares and couldn't handle the /wnups but needed the old 'legacy' fares with the up contained in the basis and not as a designator. Unfortunately what this did was break many routes, since those fares weren't even filed on them... or they were only in high buckets. So the cert ended up going up the chain until it found one, or it pulled a full YUP and quoted that as booking into A/I.
Luckily it did get fixed somewhere along the line and seems to be pretty well behaved now.