`headerCreateAll` misses some files which are covered by `headerCheckAll`

[catap]

I'm updating a license header in project for more than 200 files.

sbt headerCreateAll misses some of files, and sbt headerCheckAll fails on that files.

[catap]

Interesting, removing all copyrigth headers from the first file in the list, ublock it.

[sirthias]

Same issue here.
This is quite annoying in a large project with many sub-projects.

[leviramsey]

I suspect this is due to the Create tasks being incremental. An sbt clean before headerCreateAll seems to address this for me.