It all looks good to me. Please note just writing - [ ] at the start of a line is not valid syntax to create a checklist item. You need to have a least some text afterwards such as - [ ] item 1. I hope that helps!
Please note this generally applies to all lists. If you make a task list but do not include content, we assume it is a general bullet list and continue from there. If you create a dash (-) and do not follow that with any content, we assume you are done with the list and so remove that last dash.