On Friday we pushed an update to the LTI tools that we announced several weeks ago. A small number of institutions are reporting issues in accessing the tools. This is likely due to a mismatch in your developer key with the one that we moved into our new database related to the new LTI tools. You are welcome to try the fix listed below or we can arrange a quick call to look into this issue with you.
You will need someone who has access to read the developer key at the institution level to verify that everything matches what we have on file.
We are here and available to help in whatever way you need and, again, we're more than happy to jump on a call to help figure this out.