The fact that you're having these problems with SEB does complicate matters. Is it only with SEB? Can you replicate any of the problems with Firefox or Chrome? If so, I think it would still be useful to use the developer tools to see how long the load of the various Ace elements is taking when not coming from cache. And by the way - Firefox has a similar network tab to Chrome in its Developer Tools.
I'm surprised you're not seeing an Ace load failure message. Here's what I see if I deliberately raise a JavaScript exception during the loading of Ace. This is with the latest versions of Moodle and CodeRunner but shouldn't have changed in recent years.
I'm surprised you're not seeing an Ace load failure message. Here's what I see if I deliberately raise a JavaScript exception during the loading of Ace. This is with the latest versions of Moodle and CodeRunner but shouldn't have changed in recent years.
If you can't replicate the problem in a standard browser like Chrome or Firefox then I'm afraid I can't offer much in the way of help, as there's no way to find out exactly what is happening.