STEPS TO REPRODUCE
1. Launch iClone 6
2. Apply a random character (e.g. Heidi)
3. Apply a random motion (e.g. Idle)
4. Apply a random prop (e.g. Arc_001), place it next to the character
5. Launch Timeline, go to Frame 1, pick the character
6. Navigate to Modify > Edit > Linkage, click "Pick Parent" button, then select the Prop
7. Pick the prop, rotate it by 90 degrees
8. Go to Frame 1, Pick the character, navigate to Modify > Edit > Linkage, click "Unlink" button
9. Go to Collect Clip track of the character, select the whole motion, then right-click and choose Add MotionPlus to Library, save it to desktop

ACTUAL RESULT
Program crashes

EXPECTED RESULT
If apply motion to character, link character to prop and export it via Add MotionPlus to Library, the program can work normally