Note not loading but then loads. Then acts like read only - can't add new blocks.

Note not loading but then loads. Then acts like read only - can't add new blocks.

Hi Guys,
First time for this issue personally. I've created a note with multiple blocks, headings, lines, and urls, and PDF embeds.
At the end of the note I I'd like to add more, except I'm blocked.
What I've tried:
- refreshing chrome tab
- restarting chrome
- logging out and logging back in
- switching blocks between locked/unlocked
Do you have any suggestions?
Happy to send link and password but not a public link off this support page.

Regards,

Steve.