Hello,
This is the scenario, which we've streamlined to its simplest form while attempting to debug the issue we are having.
Simplest survey ever (a text question, "text_question", and a file question), authored with Connect 3.13.249. We publish the survey, and then create a View Layer from the layer Survey123 created. We then set up a filter on the View: 'text_question' = '1';
Users can only see and edit their own features on the layer. Users can see (but not edit) all features on the view.
We then connect the survey to the View in Connect, by introducing values for 'form_id' and 'submission_url', and republish it.
Then we submit several entries for the survey.

Now, we want to open a previous submission in "copy" mode. So, our URL looks like:
https://survey123.arcgis.com/share/<surveyId>?mode=copy&globalId=<globalId>
If this submission does NOT change the value of the attribute used for the filter, then a file can be attached and the submission succeeds.
However, if the submission DOES change the value of the attribute used for the filter (by introducing, for instance '2' as the value of 'text_question'), then we receive the following error:

Also, if the submission in "mode=copy" does NOT attach a file, then everything works as intended.
Thanks in advance.