Cal. Civ. Proc. Code § 634

When a statement of decision does not resolve a controverted issue, or if the statement is ambiguous and the record shows that the omission or ambiguity was brought to the attention of the trial court either prior to entry of judgment or in conjunction with a motion under Section 657 or 663, it shall not be inferred on appeal or upon a motion under Section 657 or 663 that the trial court decided in favor of the prevailing party as to those facts or on that issue.