Resolvido.
with
CTE_Split as
(
select
c.cdchamado,
cast(value as int) as cdsubchamadosplit
from vw_hd_chamado13 as c
cross apply String_Split(c.cdsubchamados, ',')
),
CTE_Rec as
(
select
cdchamado,
cdsubchamadosplit
from CTE_Split
union all
select
r.cdchamado,
s.cdsubchamadosplit
from CTE_Rec as r
inner join CTE_Split as s
on r.cdsubchamadosplit = s.cdchamado
)
select
c.cdchamado,
c.cdsubchamados,
FORMAT(DATEADD(minute, (c.nrtotalhoras + coalesce(sum(s.nrtotalhoras), 0)) * 60, '2000-01-01'), 'HH:mm') as totalhoras
from vw_hd_chamado13 as c
left join CTE_Rec as r
on c.cdchamado = r.cdchamado
left join vw_hd_chamado13 as s
on r.cdsubchamadosplit = s.cdchamado
group by
c.cdchamado,
c.cdsubchamados,
c.nrtotalhoras