Issues with the arpeggiator

I had a session last night, working on an orchestral score for a tv show.

Was using the arpeggiator a lot but ran into some issues.

These are the two main issues i experienced:

1. If i played a chord of 4 notes, on 1/16th, going up it would play two of each note and would often not play the 'up' pattern clearly. very strange.

2. The arpeggiator would not play back correctly after recording. Id hold a chord, get a pattern I liked, record it in and on playback id hear a different pattern. We re-recorded and ran into the same issues.

In the end i had to use audio hijack to record the audio from logic and drag it back in as an audio file.

I've not experienced this yet but it does seem to be playing up again today. Perhaps its an audio/buffer/midi latency thing. Either way its very annoying and definitely hinders the creative process.

Could anyone shed some light please?

Thanks