These problems you were experiencing make total sense. Its looking for the exact combo of Long + Outside. It doesn't exist so it goes by play frequency. That's the issue of calling pass + run percentages together.
Now if you put in some short % + medium % + outside, both of those things exist in the playbook. So it does the short vs medium rolls.
If there are no short plays in that playbook section, it'll correctly call the medium outside when that's the medium roll. If the short roll hits, and there are no short outside plays (doesn't matter if its short inside or short run/pass), then it'll go by play frequency.