Were you finally able to find what was causing the issue and get through it?
As Jean-Serge suggested, sometimes even minor errors can cause this kind of issue, or the fact that the workflow has been running many times with errors. Best thing is to create it from scratch again. If that did not resolve your issue, Campaign support team will be able to investigate it further.
Please create a new enrichment activity (not copy/paste), delete the current one, check the new internal name of the enrichment activity (temp:enrich), and reexecute. Sometimes it happens some bug in Adobe Campaign resolved by this manipulation.
If not resolved, I recommend you to open a ticket at Adobe Campaign support, it would be up to them rather community to manage your issue.
Please, first of all, you should always put an End activity in all your workflows. Otherwise, the cleanup batch process (see technical workflow documentation) can't do the cleansing operations as it should and the temporary data remains a while.
With the interim population checkbox activated, you would be able to see the result set, after an execution. Please add the End activity, relaunch it and confirm it. Many thanks.