I know the Modeler is in Alpha. Are bugs being tracked for it? I haven't found anything so far.
In the replacement activitity-explorer app that has Modeler in it, I've found some issues.
When you create a new model and go to the "deploy process definition" button, it does not handle this correctly.
Issue 1:
The Manage Deployments page shows it correctly, but the Deployed Processes page only shows the item as "process" rather than the name you gave the model.
Also, only 1 model from the modeler will be shown there as "process". If you create a 2nd model, it will replace the first one as Version 2 of "process".
Issue 2:
After shutdown and restart, the Deployments, Deployed Processes, and even instances created with the new process are retained. However, on the Model Workspace page, none of the new models are retained. This is after the db.properties and persistence.xml files have been updated to point to a persistent H2 instance.
Digging in a little bit, the MODELDATA table has a record in it for the new model, and the JSON looks complete.
In the ACT_RE_PROCDEF table, the ID_ field has "process:6:4024" and NAME_ field is blank and the KEY_ field contains "process". The DEPLOYMENT_ field has "4021"
The ACT_RE_DEPLOYMENT table has a record with ID_ = "4021" so there's a linkage between the PROCDEF AND DEPLOYMENT tables, but with the ID_ KEY_ and NAME_ fields being mangled, it explains the UI behavior.
In short, it looks like the code behing the "deploy process definition" button in the Model Workspace screen is failing to submit the data to the tables correctly.