Grouping 23.98 clips in a 59.94 project

Hello,

I am trying to create cgroup clips of 2398 material in a 5994 project. All clips share source timecode, but the sync is not accurate when the group clip is created and synced via source timecode. If I bring all of the clips into a 2398 project and group them, the sync is perfect. Any idea why this isn't working correctly?

Thanks!