DSpace 7: previously entered qualdrop value field is deleted when adding a new (emtpy) line with the same(!) qualifier and then deleting it

[f-rapp]

Description
Submission forms: Previously entered qualdrop value field is deleted when adding a new (emtpy) line with the same(!) qualifier and then deleting the newly added line.

To reproduce
1) Enter a value for a qualdrop_value field (e.g. dc.identifier.issn)
2) Use the plus button to add another line. Select the same qualifier as above.
3) Leave the newly added line empty (do not enter a value) and click on the delete button
4) Save your item

=> the original value from 1) is gone

Expected behavior
The original value(s) should stay.

Related work

[tdonohue]

I was able to reproduce this bug on the Sandbox demo site (sandbox.dspace.org) using the instructions above. The first value disappears if you click "Save for Later" and reopen the same In Progress submission.

Needs a volunteer to investigate and fix.