Issue Summary

If 'commenting permissions' are set disabled on a board, then when you start to @ mention a member in a checklist item, it does not return a list of members.

Steps to Reproduce

1. Open the board menu
2. Go to Settings
3. Click on 'Commenting' and select 'Disabled' so no one can comment or react
4. Open a card
5. Click on 'Checklist' to add a new checklist
6. Click on 'Add an item' to add a new checklist item
7. Start typing in an @ and the username of a member to mention them

Expected Results

1. List of relevant members should display after typing in @ and the first letter of their username

Actual Results

1. The list of members does not display so you can't select a member to mention from a list

Workaround

Type in the member's full username to mention them e.g.

@username

Then click 'Add' to save changes.
This will mention them successfully, but there isn't any validation until after the checklist item is added.

Alternatively, for Standard, Premium and Enterprise Workspaces, you can assign a member to the checklist item.