Indesign Links show as modified, when not modified

Hi All,

After upgrading a few users in the company to CC2018 apps, I have been getting reports from InDesign users about problems with links.

From time to time (multiple times per day) InDesign will say that links have been modified outside of the application. Often it says that about all links.

Today I managed to reproduce this on my computer and record my screen when it is happening. See the screenshots below, here is what was happening:

• I open a big indesign document, it tells me that 238 links have been modified, I choose not to update them.
• On screenshot 1: You can see the list of the link, all of them show as modified. Let's focus on BAD ICONS.ai
  • It has been created on 1st of June at 15:40, modified 5 minutes later and placed in this document at 15:58.
• On screenshot 2: I click "refresh all links" this takes a couple of minutes, and all links now show as normal. Place date of the BAD ICONS.ai link changed to the date when I updated the links.
• On screenshot 3: I saved the file, and as soon as it is done saving, all the links show as updated again.
  • Now BAD ICONS.ai seems to have been modified today, weird, because I did not make any changes to that file, or any other linked file.
• On screenshot 4: Same information in Finder dialog.
• On screenshot 5: I update the links again. Place date changes again, links appear fine.
• On screenshot 6: I save the file, close it, and the "modified date" on the file goes back to the old one...
• On screenshot 7: I open the file again, and again the links seem to be modified, even though they are not.

Anyone has any idea what is happening here?