"The specified thumbnail file is not supported." error in Notebooks
A colleague of mine created a notebook to do some postprocessing for one of my feature services and shared it in a group with me. I tweaked it a bit, and since the original was owned by him, I was prompted to save my version as a new notebook. After filling in the fields to save it, I received a "The specified thumbnail file is not supported." error and was not allowed to save the notebook. In searching all the settings for the notebook, I don't see that there's been a thumbnail saved to it (there's just the default notebook symbol showing on the item summary page). Any thoughts? My colleague was able to make the same change that I did, in his copy of the notebook, but this isn't a good practice, as I'll have future changes I'll need to make.
