Typing Trello member initials does not mention them

Issue Summary

When using the new editor typing a board member's initials will not @mention them like it did with the previous editor.

Steps to Reproduce

1. Type a board member’s initials in the card description or comments

Expected Results

Members with the same initials will appear and can be mentioned after pressing return.

Actual Results

Members are not shown when typing their initials

Workaround

Type the member’s full name instead of the initials