[OS X TeX] Saving issues with TeXShop

["M. Tamer Özsu"]

I am having a weird issue with TeXShop on one of my machines (running High Sierra, TeXShop version ). It keeps giving me the following message:

"The document “...” could not be autosaved. The file has been changed by another application.”

I also get a similar reminder when I ask for explicit save. The file is not open anywhere else with any other application. Is there some setting that I messed up possible? Any suggestions?

Many thanks.

==Tamer