Dynamic Picklist in Liferay Forms using Objects

Issue

We have created a Liferay form with Object and used the concept of dynamic picklist (data provider + picklist).
However, we're facing issues with saving the data (selected from the picklist) upon form submission. The data selected in the picklist is not getting saved.

The reason the data is not being saved for the Picklist is due to incorrect use of the Picklist.
The current versions of Liferay do not support the integration of Picklist with Data Provider as there is no integration between the Picklist and the Data Provider.
Therefore, the picklist needs to be populated manually with values, and it's not possible to do this dynamically.
Additionally, please note that Picklist is an application for creating standard lists of values that are understood across the Liferay Portal. The process of creating a Picklist includes creating the initial list and adding items to it. Once these values are defined, they can be used in supported applications.
However, as a workaround, you may leverage the concept of creating custom objects instead of picklists and then create relationships between them. These would be very simple objects, but you would need those relationships.

Creating Objects: This will help you with the creation of objects.
Defining Object Relationships describes how to set up the object relationships.
To display these relationships, the documentation, designing Object Layouts, describes how to create a layout to display the object relationships.
Using Forms with Objects
Form Rules Overview