I have the same issue regarding this case.

(

[firstname] [varchar](8000) NULL,

[lastname] [nvarchar](300) NULL,

[gender] [nvarchar](300) NULL,

[location] [nvarchar](300) NULL,

[subscription_type] [nvarchar](300) NULL

)

WITH

(

DISTRIBUTION = ROUND_ROBIN,

CLUSTERED COLUMNSTORE INDEX

)

GO

I also tried by maximizing the table length to 1000 and data length to 8000.