Indexed view in SQL Server not using indexes

Question

My schema:

I need to get count of comment for each tag.

I created a view:

create view dbo.UserTagCommentCount
with schemabinding
as
    select
        c.UserPK, t.PK TagPK, count_big(*) Count
    from 
        dbo.Comments c
    join 
        dbo.Posts p on p.PK = c.PostPK
    join 
        dbo.PostTags pt on pt.PostPK = p.PK
    join 
        dbo.Tags t on t.PK = pt.TagPK
    group by 
        t.PK, c.UserPK
go

and I created clustered unique index on this view:

create unique clustered index PK_UserTagCommentCount 
    on dbo.UserTagCommentCount(UserPK, TagPK)
go

But when I select a rows by UserPK - this clustered index is not being used:

select *
from UserTagCommentCount 
where UserPK = 19146
order by Count desc

OK. I create a simple index

create index IX_UserTagCommentCount_UserPK 
    on UserTagCommentCount(UserPK)
go

and use select with it

select *
from UserTagCommentCount with(index(IX_UserTagCommentCount_UserPK))
where UserPK = 19146      
order by Count desc

but I see the same plan

Please any ideas? Why are the indexes not used when selecting from this view?

SQL Server 2019 development