YAML frontmatter being autofilled with 'null'

What would cause all the yaml fields in a daily note to be filled with ‘null’ instead of being blank when creating a new note? It’s also rewriting tags: #DailyNote to tags: null whenever I try to edit the tag.

Sounds like the new Properties feature. Are you using the Insider build of Obsidian?

The tags: #DailyNote one might be because it’s invalid. The # marks comments on YAML, so you’ve written the equivalent of tags: . It needs to be tags: DailyNote.

No, I also had it for about a week (was Linting the whole vault twice over) and I don’t have Properties.
Not sure if it’s Obsidian or some plugin that was forcing it. I had valid YAML always BTW.

@Cheezballz Do you have some date modified updater plugin installed? It could be that one but I’m not sure.

Nope, not on the insider build. I also didn’t know the hash was not used for tags in frontmatter, I’ll keep that in mind moving forward.

It seems to be the Update Time on Edit plugin, which had not done this before. I excluded my daily notes folder and it seems ok, but I’ll keep an eye on it for other folders.

I had to ditch that plugin and opted for AlanG’s for now.
Thing is, on my iPad, the null values are still populated and a certain tag always gets double quoted (not on PC, though), but I can live with that.
The plugin you mentioned is acting crazy for me (puts in an extra instance of YAML with date created and modified at the top, which when deleted, is forced right back in).
BTW, core Obsidian should handle modified time/date anyway – apparently it’s a few lines of code.