It seems that cautionary accidentals in a different octave within the same measure depend on the rhythm. The following picture show two identical measures, except that the first B♭ is tied to an 8th and the second is not. This is somehow affecting whether or not the cautionary ♮ shows on the high B♮ on beat 4. The high B♮ on beat one is required to reproduce this bug. I attached a minimal project containing this as well.
Missing Accidental.zip (423 KB)