Since we migrated our infrastructure to Puppet 4 we have noticed that facts are not being updated on Foreman. After debug a bit the problem we found that the facts yaml files for Puppet 4 are slightly different. The important part here is "_timestamp" fact, that has been renamed to "timestamp". The next links shows the change in Puppet 4 and the Foreman code that import the facts:

• Puppet 4: https://github.com/puppetlabs/puppet/blob/4.7.x/lib/puppet/node/facts.rb#L42
• Foreman: https://github.com/theforeman/foreman/blob/1.14-stable/app/models/host/base.rb#L123

We have patched ENC script to update the json before posting to Foreman API but would be better to update Foreman code.