Although I have been using 2020 Pro for about 6 months, I have not needed the resource library until the past few days. Therefore I can't confirm that this is new. We have tried rebooting the computer, but it changed nothing. Also, it appears that we are current with updates.
It just occurred to me that the drawing I am working with was originally developed in the 2019 pro version and was upgraded when first opened with 2020. I don't know if this could be the issue?