Box zip downloads do not have the requested files

I have been trying to use the Box zip download API for bulk downloads.

I am noticing that the count of files in the zip which gets downloaded form the link provided via the "Create Zip" request is not consistent.

That is, the number of files in the zip are way less than what I requested via the JSON with file IDs.

Is there some explanation on why the zip are not being created with the exact amount of zip files requested?

(I poll the status URL and i see no skipped files, the total count increase as i keep polling but it never amounts to the actual number of files I requested, and then the entire zip download finished with much less files than requested)

(All files are accessible via the user for which I generate a user-level access token to download the zip)

(The count of files in the zip is inconsistent, sometimes there are all the files I am expecting sometimes way less)

(I am requesting multiple zip downloads at the same time with different files inside each of them which I make sure are less than 10,000 or overall does not overstep the user's total upload size)