Build caching not used with automated builds

Hi all,

I have automated builds on Docker Hub for a soft with several dependencies. Some libraries need to be built, which results in a build time of 1hr on Docker Hub. The build caching option is enabled and the logs report “Pulling cache layers for …”, but all steps are processed anyway without using the cached data (even though nothing changes in the first part of the Docker file). Caching works when using Docker locally.

Here is, for example, one of my Docker files: https://github.com/atmoswing/atmoswing/blob/master/docker/forecaster-server-ubuntu/Dockerfile
And the Docker Hub repo: https://hub.docker.com/r/atmoswing/forecaster

Am I missing something?

Thanks for your help.