Having a fieldname called "tags" causes a weird behaviour.
On save it's added a $data with consequent MySQL error because there is no "newTags" columns in my component, but just "tags".

I found out this field "newTags" is added through the function save($data) on line 1031 located in libraries\legacy\model\admin.php called on my jcook-component with the item model save function.

Strange... it is working for me.
Wich Joomla version ?

The new approach of UCM is a mess. I understand the needs, but at the end it creates a big mess.
Let's talk about it in a new topic...

In facts it is raising issue when field is not empty.

This is a very bad integration of UCM on not UCM table.
Seems really invasive this UCM feature...

Solution : do not use the name 'tags'
Or => create 'newTags' field in database.

change the fieldname is what I did as workaround.