Based on what you are describing, the inability to save could be connectivity related, or possibly a caching issue or a browser extension interfering with the site's functionality. Let's try some connectivity troubleshooting, and see if this issue occurs in other browsers, or after disabling your extensions. If the issues with saving specifically continue, please reach out to our general support team via phone. If possible, please have a screenshot of your speed test, including the More Info section, ready for the phone agent.
As for the formatting issues you are experiencing in the editor, this could be related to junk coding being built up from previous repeated copying of templates. This was more chronic in our 2nd generation editor, but it is still known to happen in our 3rd generation editor if many copies of copies of copies are being made. The simplest fix is typically to delete the text or other applicable block entirely, and insert a new one. If the issue is pervasive through your email, you may need to rebuild it from scratch, or work with phone support to reconstruct it. I'd also advise keeping the rebuilt one as a master template. This way you can copy directly from that master every now and then, or every time, to avoid running into this type of issue.