Check table & (&) does not allow dynpro checks

What causes this issue?

INCLUDE DD_CHECK_TABL_CLASS OBJECT DOKU ID TX LANGUAGE EN

How to fix this error?

Enter a table or a database/projection view as the check table if you
want to define a foreign key relationship with a check on the mask.
Alternatively, deselect the 'Check required' option.

Error message extract from SAP system. Copyright SAP SE.