PC files don't open properly on Mac

I created a pde file on a PC and saved in Dropbox. When I open the file with Processing on a Mac (Apple silicon) the tabs open correctly but all the code is missing.

If I create a file on the Mac, save to Dropbox, open on PC, edit on PC, save back to Dropbox, then open on Mac, it works as it should.

Is there some setting I am missing?