Kinesis Video WebRTC Storage /joinStorageSession 500

When calling /joinStorageSession I get a response of {"message":"An internal failure has occurred !"} and a 500 status code on about half of requests. The other requests work as expected. This occurs both in my own test application and in the demo application here. The relative code for the linked demo is the joinSession function within the master.js file. I was wondering if this is a known issue with the webRTC ingestion preview mode and if there's anything I could do to get more consistent performance.