Ok, I think I've figured out the issue. It has only been since version 2027 that you can keep an iso template in an external location (for collaboration projects). Before version 2027 all iso.dwt's are hosted in the respective isostyle folder - so you should see the 2026 link pop up to the collaboration cache folder (see my screenshot)
https://help.autodesk.com/view/PLNT3D/2027/ENU/?guid=GUID-26681974-1D65-415B-B10A-B9EBB68C3117


In 2026 when uploading a project there is a check that will force you to keep the iso template inside the project folder.
In 2027, if your iso.dwt is coming from inside the project folder / iso style folder - you will only see a truncated version. If your iso.dwt is coming from an external location you will see the .url
There is functionally no change. When you create a new project you either choose an iso.dwt that is local inside your SQLite project before loading it up to ACC, or you later modify it to an external location.

There is no change in existing functionality and no added risk. If you only see iso.dwt it means it is the iso file inside the isostyle folder in your collaboration cache. If you see an url: it means the iso.dwt is held in an external location. the only thing changed is that you don't see the full url, but the relative url based on the location of your isostyle folder.
Your .dwt reference is NOT set to the original location. You can check this by entering 'setup title block' then right click on the 'iso.dwt' tab that is opened and choose 'Open File Location' you will see that the file location opened is the correct one, just like in 2026.
