I have the same issue with the error "this file has been modified outside of Illustrator," even though it has 100% NOT been modified outside of Illustrator. The issue began immediately after I upgraded to High Sierra 10.13.3. My files have always been backed up on Dropbox and no other user has access to these files but me. I never had this issue before the upgrade and I'm using the same files from the same location. (I use CS6 so please do not tell me to upgrade to CC. Our company is too small to pay an extravagant monthly fee for 2 users). Please fix ASAP! Thank you.
I have the same issue with the error "this file has been modified outside of Illustrator," even though it has 100% NOT been modified outside of Illustrator. The issue began immediately after I upgraded to High Sierra 10.13.3. My files have always been backed up on Dropbox and no other user has access to these files but me. I never had this issue before the upgrade and I'm using the same files from the same location. (I use CS6 so please do not tell me to upgrade to CC. Our company is too small to pay an extravagant monthly fee for 2 users). Please fix ASAP! Thank you.