I am working on a LF Flow based on modern designer that would performs the following steps:

1) A form where users can upload a number of files. The form also has a collection that will used later enter in the flow to capture details about uploaded files. The collection is empty and hidden in this step

2) A "Save to Repository" step to upload the files into Laserfiche repository

3) A workflow that checks the files have been uploaded correctly and returns the list of uploaded files to the Forms instance, using the collection variable from the form in step 1)

4) A user task, using the same form as step 1), where users enter detail about each file, using the collection fields (the colection is made visible, and now contains a number of rows equal with the number of uploaded files, and has several fields some of whihc have Field and Lookup rules). 

The form at step 4 is displayed as expected, but users cannot submit it, as it fails with the following errors:

Laserfiche Forms has encountered a problem.

Errors encountered during forms submission:

Field Name: Field1, Position: 37, Error: Invalid number of rows in collection/table. [LFF9313-InvalidNumberOfElementsInCollection] [LFF9312-ErrorOccuredDuringFormsValidation]
Field Name: Field2, Position: 30, Error: Invalid number of rows in collection/table. [LFF9313-InvalidNumberOfElementsInCollection] [LFF9312-ErrorOccuredDuringFormsValidation]
[...]

[LFF9320-FormsValidationAggregateException]

Any suggestions to fix this please ? Another discussion thread suggested to disable the Backend validation on the form, but since I am using the modern designer, I can't find a way to do this...

Forms version is 11.0.2311.50585

Thank you !