Thanks for the clarification.
In my knowledge, the XMPie composition engines do not support IDMS files as Assets.
At least, could we not find any explicit reference in the XMPie documentation.
However, I noticed a quite weird behavior with CC-2025 / 25.3: should you define a Graphic Content Object that explicitely refers to an existing IDMS file (with the ".idms" extension, specified in the QLingo rule), then... surprisingly enough, the XMPie engine injects the contents of your IDMS file into your VDP InDesign document.
It's certainly a non supported behavior which, as such, comes with several unwanted results, such as:
- in the WYSIWYG UI, the previous injections are not "cleared", so multiple IDMS renderings appear atop eachothers
- in the output file... only the first injection appears
But maybe XMPie would welcome a Feature Request?
Meanwhile, may you consider exporting to PDF? (instead of to InDesign Snippet)