Handling Locked Standard Objects (custom fields that never materialize)

The trap

Some standard industry / Financial Services Cloud objects — confirmed on the standard Claim object (KeyPrefix 0Zk) in the CommericalDemos org — are structurally locked: you can create custom fields on them through every normal channel and get success every time, but the column never physically exists.

• A CustomField metadata deploy returns success: true.
• A Tooling API POST to /sobjects/CustomField returns created: true.
• EntityDefinition.IsCustomizable reports true.
• …and yet the field is invisible to SOQL (No such column), to REST describe, and to Apex Schema.getGlobalDescribe().get('Claim').getDescribe().fields.getMap() — a field "created" seconds earlier returns false from .containsKey(...).

This is structural (a locked managed/standard object), not a propagation delay or cache staleness. Waiting does not fix it. The "created" field records are orphaned metadata no-ops — harmless, but never queryable.

Detect it before you design around it

Don't trust the deploy's success:true. Prove the column exists at runtime with Apex getGlobalDescribe — this is the authoritative check: