Thank you for your patience all this while, We have concluded our investigation into the issue and below is our finding.
This issue is due to the use of a specific version of Extensis Universal Type client: version 6.1.6.
The issue is reproducible only with Id 2018 as Extensis UTC 6.1.6 is not compatible with Id 2019.
If you are using Extensis UTC 6.1.6 with InDesign 2018 please use any other version of Extensis UTC which is compatible with Id 2018 to avoid this issue.
Or you can upgrade to Id 2019 and used compatible version of Extensis UTC.
InDesign TeamAmybethM commented
I am at the beginning of an enterprise deployment. Indesign CC2018 on Mac High Sierra.
See Reported Bug notes:
BUG REPORT NOTES,
INDESIGN FILES ARE LOSING THEIR LINKS—
If I open from Indesign idml, the file can update links,
and the option to “find other missing links in this folder?” Is disabled.
Then, if you open an Indesign.indd file, the
File forgets its links,
If you relink, and save the file, it forgets it’s links all over again.
My workaround has been to open from idml,
update links, export again as idml, save the indesign file.
I still need to open from the idml. So, it kind of makes the indesign file redundant.
The worst part of this is that when updating the links, the option to “find other missing links in this folder?” Is disabled.AmybethM commented
I have the same issue