Add Flag on a card in Board doesn't work correctly if the Flagged field is hidden initially and then marked as Show

Issue Summary

This is reproducible on Data Center: (yes)

Steps to Reproduce

1. Create a Board.
2. Open the Board and "Add Flag", you will notice that the flag will get added fine.
3. Now, go to the Project settings > Fields > Actions > Edit fields.
4. Search for Flagged field and click on Hide.
5. Go back to the board, you will notice that the Flagged that was marked before hiding the field is shown.
6. Now, try to add flag to another issue, you will notice that the flag is not shown but behind the scenes, Flagged field is being set to value Impediment.
   
   So technically the flag is set for that issue. It's just not showing on the board. May be  because the field is marked as hidden, its not showing. But do note here, that the flag which was marked before the field was marked as hidden is still showing the flag fine.
7. Now, if you go back to the same issue in the Board, it will still show you the option of Add flag which doesn't seems correct. It should for remove flag.
8. Now, make the field as visible by following same steps in Point 3 and 4 above.
9. Come back to the board, refresh the page and for the same issue which you marked as flagged in point 6. It will still not show the flag. 
10. Now to come out of this situation, you need to clear the value Impediment that is set for the field Flagged,. One way to remove it is to do, Add Flag and comment as that will remove the flag and then add it back again with the comment and after this point onwards, the addition and removal of flag just work fine for that issue.

Expected Results

1. There is some discrepancy here in how the Flag visibility works in the Board.
2. First point, once the field is marked as visible, the flag should be shown for the fields where flag was added when the field was hidden.
3. Second point, once the flag was marked for the issue when the Flagged field was hidden, the next time user goes back, it should show remove flag option as add flag can't work as Flagged field is already set to Impediment. 

(This is not version specific issue and seems to be the same behaviour in all Jira versions)

Actual Results

Refer to steps to reproduce.

Workaround

Make the Flagged field visible and then come to the affected issue and click on Add flag and comment once and then from this point onwards, Add Flag functionality will work fine for all subsequent flag additions and removals.