getting nulls when concatenating string columns in pyspark. Why?

I have this super simple dataframe: rc1.show(5) rc1.printSchema() +——–+———–+ | ID|Case number| +——–+———–+ |11034701| JA366925| |11227287| JB147188| |11227583| JB147595| |11227293| JB147230| |11227634| JB147599| +——–+———–+ only showing top 5 rows root |– ID: string (nullable = true) |– Case number: string (nullable = true) I want to add a new column that is just the concatenation…

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