Duplicate category name on same level cause the issue.
Not sure if you have access on your DB to execute a Select Query,
If yes, this query will help you to find out problem creating categories.
WITH CTECategoryHierarchy(LeafCategoryId, FullName) AS (
SELECT Id, CAST(Name as NVARCHAR(MAX)) FROM Category WITH (NOLOCK) WHERE ParentCategoryId = 0 AND Deleted = 0
UNION ALL
SELECT c.Id, h.FullName+' > '+c.Name
FROM Category c WITH (NOLOCK)
JOIN CTECategoryHierarchy h ON h.LeafCategoryId = c.ParentCategoryId
),
CTEFinalData AS(
SELECT c2.Id, c2.Name, cs.cts.query('root').value('.[1]', 'nvarchar(max)') AS 'CategoryHierarchy'
FROM [dbo].Category c2
CROSS APPLY (SELECT ch.FullName + '; '
FROM Category c1
JOIN CTECategoryHierarchy ch WITH (NOLOCK) ON c1.Id = ch.LeafCategoryId
WHERE c1.Id = c2.Id
order by c1.Id
FOR XML PATH(''), root('root'), type) cs (cts)
WHERE c2.Deleted = 0 AND (SELECT COUNT(Id) from Category c WHERE c.ParentCategoryId = c2.Id) = 0),
MultipleCategory AS (
SELECT
cc.*,
ROW_NUMBER() OVER (
PARTITION BY
[Name],
CategoryHierarchy
ORDER BY
[Name]
) Total_Count
FROM
CTEFinalData cc
)
SELECT * from MultipleCategory where Total_Count > 1 order by Total_Count desc