data not saved in one to many when entered in form of refEntity and form of refEntity is saved (8.6.2)

[BrendaHijmans]

How to Reproduce

Upload provided data model
one_to_many_issue.xlsx

1. Add data in form entity gc_growthCards, save
2. Edit newly made row then enter data for attribute graph data length (one-to-many relationship to other table)
3. Click create
4. Click save changes

Expected behavior

Newly entered data is saved

Observed behavior

Newly entered data is not saved

NOTE: when form is not saved (click cancel at step 4 or exit via 'x' in upper right corner)
data is saved!