Our experience with Maven Central at Sonatype is poor: releases disappear or are unexplicably delayed.
If you must use Maven Central by Sonatype, you should contact them regarding your issues. We do our best to release our artefacts. As you can see, some of our releases make it, some do not. It is entirely out of our control.
I have had others independently verify the problems that we have encountered. In my opinion, Maven Central should be considered a legacy component best to be removed for our workflows.
JCenter is much faster, much better managed. There is simply no reason other than inertia to stick with Maven Central.
Of course, we will continue to do our best to push to Maven Central, but the artefacts might be missing or delayed. Again, there is nothing we can do about it.