Hello @BTBT
Thank you for reaching out to the Community regarding your issue, although I am sorry to hear that you are experiencing issues with Principal funds. I was taking a look to see what the error could be but I was getting an invalid login with fake credentials which is expected. That being said your error is after signing in so it should be a bit different. I believe it would be best to collect logs to figure out what exactly is happening. You should be able to submit them by going across the top to help > report a problem. You'll want to have all logs selected (Should be selected by default).
Once you've done so please let us know and we'll see what we're able to find out in the logs.
Thanks,
Quicken Francisco