BUG: Dragging on the "board" view sometimes loses tags or assignments

Hello, there are two parts to this bug.

1. Viewing a sublist "by tag" is an extremely cool way of managing complex statuses. Normally, the logic works quite well dragging between columns: if a task is tagged TagA and TagC, and I drag it from column TagA to TagB, now it's tagged TagB and TagC. This is perfect. It removed the "old" status and gained the "new" status, and the other tags were left intact. HOWEVER, sometimes and for no apparent reason, TagC gets wiped out in this scenario, and it becomes very easy to screw up carefully tagged tasks.

2. If I view a sublist on the board, and "Group By Assignee"... if a task has multiple assignees, it doesn't matter where I drag the task, assignees will be wiped out and only one will remain. It should work the same as described above: Remove the assignee from the column or row the task was dragged from, and add the assignee of the row or column the task was dragged to, and leave all other assignees alone!

Thanks, hopefully this is just a bug and can be easily resolved!