Can I mark a missing assignment as "Missing" (changing the color to pink/reddish and entering a grade of 0) for all students at once? If so, how?
Can I mark all past-due assignments as "Missing" in a course at once?
For my use, this is for the assignments with "no submission" such as for an inline Google Form rather than an upload or Google Drive attach option.
You can use the late missing policy to automatically add a zero and missing tag to missing submissions at the due time. The settings are in the gear icon on the grades page.
Assignments that are not submitted through canvas will not be included. You can bulk enter zeros from the three dot menu on the title of each assignment. The option is called "set default grade." Just be sure you do not set it to overwrite existing grades, and it will fill in every blank with whatever default score you enter. It will not currently turn on missing tags, so that part would need to be done manually if desired.
There are several ideas open about this topic that you might want to contribute to: