Google BigQuery中的“糟糕的双重价值”

I'm working in Google BigQuery (not using LegacySQL), and I'm currently trying to cast() a string as a float64. Each time I get the error "Bad double value". I've also tried safe_cast() but it completely eliminates some of my id's (Ex: if one customer repeats 3 times for 3 different dates, and only has 'null' for a single "Height" entry, that customer is completely eliminated after I do safe_cast(), not just the row that had the 'null' value). I don't have any weird string value in my data, just whole or rational numbers or null entries. I'm working in Google BigQuery (not using Legac