Can’t preview or safe any changes

Hi!

I’m trying to edit my “maintenance mode” page because after the latest plugin updates, the logo is not showing, and the tweet feed I had set is missing (I think I lost some code after the plugin major update).

The problem is that I cannot preview my page or save any changes, I’m getting this error every time I try to do it:
Something has prevented the page from being saved. The host you are using may have a security setting preventing it from being saved. Refresh the page and try again

I’ve refreshed my site several times, what could be happening?

Thanks, regards.