I do not usually get noticable intonation problems on that string.James Lister wrote: ↑Thu Aug 31, 2017 8:20 amTwo possibilities I can think of.
1. The "bad" part if the string was initially near the bridge, and with the string reversed it was on the tuner rollers, and so had no effect.
2. Your guitar has a slight intonation problem, and the faulty string made it worse, but when reversed made it better.