Hi,
Please check the other blog post. On that post it is indeed missing but at the other it is certainly present.
The php log contains no errors. I'm also using New Relic which also captures any errors but none are related to this website.
For the time being I shall exclude the files. Thanks for the help so far!
Fyi, I've also tried the "AUTOPTIMIZE_LEGACY_MINIFIERS".
Yours sincerely,
Tim