If no collection table is specifically mapped and an entity name is specified (via @Entity(name="...") , the table name generated for @ElementCollection starts with its (unqualified) owning entity class name. It should start with the mapped entity name instead.
Currently, the collection table is named "Matrix_mvalues"; it should be "Mtx_mvalues".
This was fixed in 4.3 and 4.2 by HHH-9280.
org.hibernate.test.annotations.collectionelement.CollectionElementTest.testDefaultTableNameUsesJpaEntityName() reproduces this issue and is marked @FailureExpectedWithNewMetamodel.