I went to create a page on my basic Hub site today. I clicked on new page, added the title and clicked Next. It appears the page is created as the template for a new page appears. I made a couple small edits, then clicked on Save, then View. The View links to "null" - there is no address (just "null" in the address) so a blank page opens in the tab with an error. Then when I go back to the list of pages in the Hub, the new page is not there, only the two existing ones. I have only had it open in one tab and I haven't been working on this site in a couple weeks at least.
Seems like something on the back end perhaps?
Edit: It seems to be specific to this Hub as I just tried to add a page on a different Hub and it worked as expected.
Just thought I'd give you a heads up, as of June 22, 2020 the bug has been fixed. Let us know if this is still happening, if it is you might need to open a Support Ticket for the issue.