After upgrading I'm not able to Overwrite pictures when exporting the same picture for a second time

After upgrading to Lightroom Classic CC (version 7)  I'm not able to Overwrite pictures when exporting the same picture for a second time. A window pops up that reads: "Export Results. Some export operations were not performed. The file could not be written. (2)". followed by the list of the 2 specific files I'm trying to export. I've tried closing Lightroom and going back in again. T. Tried with "Export" and "Export with Previous". Got same results. The files are not being opened by another app that could be locking them. They are not "read-only" either. Help will be greatly appreciated.