Checklists are broken

[bigfish24]

Create a post with checklist items:

It saves and renders without the checkboxes:

Then I reload the page:

I complete a checklist item:

Then I reload the page:

If I complete another checklist item:

But then do not reload the page, I am left in a broken state, such as if I try to add another item (or delete one):

I get this error:

[bigfish24]

Note I am on Chrome: Version 72.0.3626.121 on MacOS 10.14.3

[gracie]

I've found this happening on our team p2 as well. When I check a checkbox, all the checkboxes disappear. @benchilcote has been experiencing it as well - I think it's across the board.