Following the Support TicketID 267281 here.

The CC5's version is 5.03.
Just open it, load Ariana Clothed and do InstaLOD > Polygon-reduction Wearables.

Here's the video:
https://youtu.be/q4tQjU18PT4

It does with other characters too and sometimes it corrupt the project and cannot be loaded again.

It crashes with Polygon reduction object as well:
Open _HD_Ariana_Clothed and do a Polygon reduction object on the eyelashes. It will crash as well.
It happens with eyelashes and beards. It also crashes doing Remeshing with 3 LOD levels (I suppose it's the same bug).