This is probably the same issues experienced in JENKINS-55814

Since this version, we now see text like the following in a lot of our builds:

[2019-03-11T13:51:57.733Z] MicrosoftAzureStorage - Need uploaded/archived file count = 11
[2019-03-11T13:51:57.733Z] MicrosoftAzureStorage - Uploaded/archived file count = 10

The missing file is almost always the largest one out of a set.

I'm able to reproduce the effect locally, and the "missing" file upload appears to happen at the end of the upload - i.e. lots of data is transferred, but never reflected in the blob container. I'm going to continue working through the problem in a debugger to better isolate exactly what broke.

Please ping me via Teams if it helps speed up tracking the problem, it's badly affecting multiple groups for us here.

For an "easy" repro, try a job which uploads one very small file, and one very large file (hundreds of megabytes)