There's a known bug that is being investigated right now by Microsoft/Asobo, which seems to affect lots of 3rd party sceneries, which is the infamous "60% freeze on load".
What we know is:
- It doesn't happen every time. If the scenery had a problem, it should always happen but, instead, it seems to happen about 30% of the time.
- It doesn't happen with a specific product, we read reports of this happening with multiple sceneries from different developers.
- The problem seems to be fixed entirely by disabling "Online functionality".
- The sim might not be REALLY locked up because, some users reported it eventually loads, possibly even taking an hour or so.
- When the sim appears to be frozen, is in fact doing something, since there's some activity on the network, connecting to Azure, just at a *very* slow speed, which might explain why it eventually comes up after a long time.
We have supplied all this information to Asobo so, hopefully they will come up with a fix for the next update.