One of our Dynamics 365 customers faced an issue where the “Buttons to create the products were missing in UCI App and also when opens the existing records, it shows as ‘Read Only’ in (Sales Hub) but works in Legacy app”. In our cases, we had this issue with ‘Products’ entity but this can happen for other entities as well.

“Create” buttons are missing

Forms shows as Read Only even when accessed with ‘System Administrator’ role

Further analyzing this issue, it was found that the entity has the below option checked.

Read-only in Unified Client – Checked

As a fix, ‘Read-only in United Client’ should be unchecked and entity to be plublished. Once done, Create buttons would appear:

Also, this has been documented in detail here:

Hope this helps!