Y-Phil, are you running Sonoma?  I got a reply from  Poser customer support stating:

"We are currently investigating the Hierarchy Editor drag crash. It's repeatable here partucularly updating to Sonoma 14.6.1 or higher. It also occurs in Sequoia 15. Prior to that the crash did not occur in Ventura 13 or Sonoma 14.5.

In the past Poser 11 and 12 have become unstable when Sonoma 14 was introduced to the point that they are unusable in Sonoma 14. It seems that Poser is getting worse each time they update the Mac OS.

We will continue to investigate why Poser 13 is becoming more unstable with Sonoma 14.6.1 and higher.
You may request a refund of Poser 13 in the meantime.

Sorry for the current inconvenience that is beyond our control with the Mac OS."