When using the m365 spo page header set command, it removes any web part which has already been defined on the page. So you'll end up with an updated header, but no page content.

Tested with various web parts.
Run m365 spo page header set for a page that has already been configured. Once you ran the command, all configured web parts are gone.
Only the header should be updated.

That's a bad one! Thanks for reporting it and sorry for the trouble. Let's get it fixed asap!
Working on a fix, already found the issue.
Ouch, thanks for reporting and taking a look at a fix 馃檶
I've assigned the issue to you so we don't double efforts 馃憤
Awesome! Appreciate your help @estruyf 馃憦
Most helpful comment
Working on a fix, already found the issue.