when uploading a dxf or a dwg to sketchup web, it only accepts files where the extension is in lowercase.
this is the same file, lowercase imports, uppercase returns an invalid file type.
I haven’t seen this issue with PNG and png, only dwg/dxf
On Mac or PC? Windows filenames shouldn’t be case sensitive. On the Mac, I understand that you can choose at OS level whether they are or not, and historically, SketchUp has had problems with the case sensitive option.