Was waiting on the  Update 2 patch before switching to 2021. Got it loaded up and configured. Built some models, programmed the part, then went to merge in models from another file using "Shift and drag" to merge the file into the Mcam window from explorer. (Something I've done thousands of times before) File was saved, then went to re-open the file and now get this with no models now:   Any ideas what causes this?   Not a good start with 2021..