I need some help to adjust +, -, and ? symbols for low, high and unclear risk of bias for Cochrane risk of bias assessment in meta-analysis using RevMan Review Manager software 5.3.

When I generate the risk of bias table, only the +, and - symbols are seen but not the ? symbol for unclear risk of bias. I know the risk of bias table is a auto generation but there must be reason why the symbol ? is not appearing?

Any suggestion please to resolve it?

Thanks in advance