Synapse SQL - Index creation is extremely slow for a small table

I attempted to create a nonclustered index on a small table in synapse. It was running for was running 15 mins and started to block sessions, so I cancelled it.   The FACT_NON_MERCH_DISCOUNT table had only 25,597 rows, so normally an index creation on that should be very fast in a sql server instance.  This is the TSQL used.  

CREATE NONCLUSTERED INDEX [NCI_BUSINESS_DATE] ON [bnbi_retail].[FACT_NON_MERCH_DISCOUNT]
(
                [BUSINESS_DATE] ASC
)WITH (DROP_EXISTING = OFF)
GO

I did a second test and cancelled after 20 minutes.  Can you tell me what could be causing a small new index to run so long?  Attached are some screen prints showing the resources are good and the locks created.  A larger table recommended has over 61 million rows, so I need to know the root cause for the excessive runtime of an index creation, before attempting anything that large.  Also, attached is the DDL for the existing table with the existing Index and the distribution settings that pre-existed for the [bnbi_retail].[FACT_NON_MERCH_DISCOUNT] table.

Here is the reversed DDL for the preexisting table I tried to add the nonclustered index to.:
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [bnbi_retail].[FACT_NON_MERCH_DISCOUNT]
(
[TRAN_KEY_ID] [bigint] NOT NULL,
[NON_MERCH_SEQ_NUM] [int] NOT NULL,
[NON_MERCH_DISCOUNT_SEQ_NUM] [int] NOT NULL,
[BUSINESS_DATE_INT] [int] NULL,
[SK_MEMBERSHIP] [bigint] NULL,
[DISCOUNT_ID] [varchar](20) NULL,
[DISCOUNT_AMT] [decimal](9, 2) NULL,
[DISCOUNT_PCT] [int] NULL,
[DISCOUNT_TYPE] [int] NULL,
[DISCOUNT_CALCULATION] [int] NULL,
[DISCOUNT_SOURCE] [int] NULL,
[PROMO_ID] [char](10) NULL,
[DISCOUNT_TYPE_EXTENDED] [int] NULL,
[ENTITLEMENT_TYPE] [char](10) NULL,
[SK_SOURCE_FEED] [bigint] NULL,
[CREATE_DATE] [datetime2](7) NULL,
[UPDATE_DATE] [datetime2](7) NULL,
[CREATE_USER_ID] [varchar](100) NULL,
[UPDATE_USER_ID] [varchar](100) NULL,
[FILE_NAME] [varchar](250) NULL,
[ETL_LOAD_ID] [int] NULL,
[BUSINESS_DATE] [date] NULL,
CONSTRAINT [PK_] PRIMARY KEY NONCLUSTERED
(
[TRAN_KEY_ID] ASC,
[NON_MERCH_SEQ_NUM] ASC,
[NON_MERCH_DISCOUNT_SEQ_NUM] ASC
) NOT ENFORCED
)
WITH
(
DISTRIBUTION = REPLICATE,
CLUSTERED COLUMNSTORE INDEX
)
GO