Hi ,
I was able to reproduce your freezing bug. Unfortunately, we found a host of other problems including rendering and crash problems along with it. I have attached this conversation to several bug reports to be assessed, but these may take some time to parse through and discover what may be occurring. On a side note, I wanted to provide to you some information that may be useful:
I believe that level streaming would be extremely beneficial to you during this project. I noticed that you have a lot of objects set up in your persistent level, which is definitely contributing to the rendering bug we came across (when there is a large amount of foliage in a level they begin to glow bright emissive colors). By separating these out into separate streamed levels you will save yourself a lot of space and processing, which may help improve performance by a large margin in the long run. For now, however, I would recommend working on other areas of your game until we can figure out what exactly is causing these problems that you are experiencing. We will post here when we have more information on the bug.