Unreliable Google Docs copy-paste in Safari

I'm using Safari and copy-pasting in Google Docs with a keyboard shortcut is extremely unreliable. It can work most of the time, but at some point the Cut and Copy items in the Safari menu become disabled and the only way to get copy-paste working again is to reload the page.

Is there any way of getting copy-paste to work properly in other browsers, or is using Google Chrome the only solution, as described in this topic: https://webapps.stackexchange.com/questions/40147/in-copy-paste-google-docs-says-these-actions-are-unavailable-via-the-edit-menu

I’ve found that rather than reloading the entire document, simply changing it in any way (e.g. entering a space somewhere) re-jiggers it so that copy will work again…

Until it doesn't (usually one time), and you get the “beep” and then you have to type something again.

Annoying, but far less annoying than reloading the entire doc each time this happens.