Cannot add issue to a board associated with a milestone

Scenario 1

• Go to this board: https://gitlab.com/victorwu/project-delta/boards/279510
• This board has an associated milestone, M2.
• Add any existing issue with no milestone to the board using the Add issues button
• The issue should have the associated milestone added to it, this does not happen
• As a result, the issue is added to the board, but after a refresh, it disappears

Scenario 2

• Go to this board: https://gitlab.com/victorwu/project-delta/boards/279510
• This board has an associated milestone, M2.
• Add any existing issue with milestone M1 to the board using the Add issues button
• The issue should have it's milestone changed to M2, but this does not happen
• As a result, the issue is added to the board, but after a refresh, it disappears

Scenario 3

• Same thing as above, but for a board without an associated milestone, but a dropdown filtered milestone
• When a dropdown milestone is selected, adding an issue to the board should change the issue's milestone to that milestone