Error Saving GPT with 8 Files

I am trying to build a GPT with 8 files, each is less than 11MB. I cannot create it when I upload all files at once.
When I start uploading file by file, it works, but after adding about 2 files I cannot save/publish any additional files. The dreaded: “Error Saving GPT”.

Browser Dev Tools show:

Failed to load resource: the server responded with a status of 504 ()
_app-256f6a789863880e.js:26 Failed to parse error response SyntaxError: Unexpected token '<', "<html>
  <"... is not valid JSON
eU.<computed> @ _app-256f6a789863880e.js:26
_app-256f6a789863880e.js:26 FatalServerError: Something went wrong. If this issue persists please contact us through our help center at
    at _app-256f6a789863880e.js:26:2519431
    at c (main-abb0536823058f9d.js:1:107151)
    at u._invoke (main-abb0536823058f9d.js:1:106931)
    at e.<computed> [as throw] (main-abb0536823058f9d.js:1:107554)
    at ei (_app-256f6a789863880e.js:75:109675)
    at ed (_app-256f6a789863880e.js:75:109934)
eU.<computed> @ _app-256f6a789863880e.js:26

I get the same Error with 11 Files.
I get the following messages:

Does anyone know the answer to this?

I got the model to work by reducing the number of files to 5. After the first publishing I was able to add a sixth file, but with the seventh file, i got the same error again. So I guess the limit of files to upload is six.