@HSheild
Yes, I have published it. Performed Publish all customization for the new solution multiple times. For the time being I have disabled field security and put up a read only field on the form.
For the reference, I had an issue were a field which had a Business rule (in CDS), business rule was not executing since the same field was updated through a flow also. So I had to remove the Business Rule from that field-1 and set it to another field-2. After that the solution was working as expected.
Would there have been a case were the field security profile fails to work due to any CUSTOM ROLE?
As of now I have a custom role created based on the CDS user role(standard role) with Create, Read & write access to the new entity. Since it is a new solution I don't have much objects and only 1 customized role.