I got an error today while importing a bunch of Smart Materials into my project, this one here

After receiving this error, it's no longer possible for me to drag files straight into Painter to import them, the mouse just shows that crossed out circle cursor. Restarting Painter, the PC, making a new project, etc have not worked to restore my ability to do this. The only way for me to import now is using the Import Resources option in the File menu.