I figured it out. I added an ID for category and partitioned by category_id and project_id.
with
t1(rowNum, PROJECT_ID, NAME_LAST, NAME_FIRST, POINT_OF_CONTACT, PROJECT_NAME, CATEGORY_ID, CATEGORY_NAME) as
(
SELECT
RowNumber() over (PARTITION BY F13.DIM_PROJECT_ID, F13.CATEGORY_ID ORDER BY F13.PROJECT_NAME, F13.CATEGORY_NAME),
F13.DIM_PROJECT_ID,
F2P.NAME_LAST,
F2P.NAME_FIRST,
REPLACE(F2P.POINT_OF_CONTACT, ',', ' |') AS POINT_OF_CONTACT,
F13.PROJECT_NAME,
F13.CATEGORY_ID
F13.CATEGORY_NAME,
FROM FACT_TABLE AS F13
INNER JOIN ADMIN AS F2P ON F13.DIM_PROJECT_ID = F2P.DIM_PROJECT_ID
LEFT JOIN HOURS AS F2H ON F13.DIM_PROJECT_ID = F2H.DIM_PROJECT_ID
WHERE F13.CATEGORY_NAME = ('INVISION')
group by
F13.DIM_PROJECT_ID,
F13.PROJECT_NAME,
F2P.NAME_LAST,
F2P.NAME_FIRST,
F2P.POINT_OF_CONTACT,
F13.CATEGORY_ID
F13.CATEGORY_NAME
) ,
t2(PROJECT_ID, LIST, POINT_OF_CONTACT, PROJECT_NAME, CATEGORY_ID, CATEGORY_NAME, cnt) AS
( SELECT PROJECT_ID,
VARCHAR(NAME_FIRST CONCAT ' ' CONCAT NAME_LAST, 6000),
POINT_OF_CONTACT,
PROJECT_NAME,
CATEGORY_ID,
CATEGORY_NAME,
1
FROM t1
WHERE rowNum = 1
UNION ALL
SELECT t2.PROJECT_ID,
t2.list || ' | ' || t1.NAME_FIRST CONCAT ' ' CONCAT t1.NAME_LAST,
t1.POINT_OF_CONTACT,
t1.PROJECT_NAME,
t1.CATEGORY_ID,
t1.CATEGORY_NAME
FROM t2, t1
WHERE t2.project_id = t1.project_id
AND t2.category_id = t1.category_id
AND t2.cnt + 1 = t1.rowNum )
SELECT PROJECT_ID,
PROJECT_NAME,
POINT_OF_CONTACT,
CATEGORY_ID,
CATEGORY_NAME
list
FROM t2
WHERE ( PROJECT_ID, CATEGORY_ID, cnt ) IN (
SELECT PROJECT_ID, CATEGORY_ID, MAX(rowNum)
FROM t1
GROUP BY PROJECT_NAME )