I’m a little confused as to what is causing this.
I keep having the same issue where several creatures are getting stuck at the same coordinates for no apparent reason. I thought I had corrected the issue by deleting and replacing the building pieces. However; it appears to be random as to the coordinates and occurrence frequency.
@Endoproxy Thank you for your report! We would like to look into this further, would you be able to submit a bug report using the form available here? Fortnite Creative