Joining Aggregate from table through join with another table - T-SQL (3 tables in total)

I have 3 tables:
A : jira_unresolved_sales_issue_v - my 'main table'
B : jira_causes_links_v - my 'connecting table'
C : jira_invoices_v - table where I want to take SUM with
A connects to B with A.id (unique) = B.srcID , B connects to C with B.dstID (unique) = C.issueid (unique)

So I want to add (left join) some sum of invoices from table C to table A.

Table A:

Table B:

Table C:

What I want to achieve is Table A like this:

I tried code :

select  A.id, sum(C.Amount) as amount
from A
LEFT JOIN B on A.id = B.srcID
LEFT JOIN ( Select C.issueid, sum(C.amount) as amount
FROM C
WHERE C.status <> 'Canceled'
GROUP BY C.issueid) as C on B.dstID= C.issueID
GROUP BY A.ID, C.amount (sum of amount)

But this kind of give me too many rows. It doesn't actually SUM per my A.ID. I know I am close, just missing something.

You seem to be over-complicating things, the following should be all you need

select a.Id, s.Amount
from a
outer apply (
	select Sum(amount) Amount
	from c join b on b.dstid = c.issueid
	where b.srcid = a.id
)s;

When asking questions like these it's really helpful to provide reproduceable DML/DDL. I favor table variables for this personally, because there's less to clean up.

DECLARE @TableA TABLE (id INT, otherCol NVARCHAR(10));
DECLARE @TableB TABLE (srcID INT, dstID INT);
DECLARE @TableC TABLE (issueid INT, Amount INT, status NVARCHAR(10));

INSERT INTO @TableA (id, otherCol) VALUES (1, 'sxacdfa'), (2, 'xasdafa');
INSERT INTO @TableB (srcID, dstID) VALUES (1,3), (1,4), (2, 5), (2, 6), (2, 7);
INSERT INTO @TableC (issueid, Amount, status) VALUES 
(3, 3000, 'Open'), (4, 200, 'Open'), 
(5, 100, 'Open'), (6, 50, 'Open'), 
(7, 1000, 'Cancelled');

I'm not sure why you feel there's a need for a sub query here, from what you described it's just a pair of LEFT OUTER JOINs, and then an aggregate:

SELECT a.id, SUM(c.Amount) AS Amount
  FROM @TableA a
    LEFT OUTER JOIN @TableB b
	  ON a.id = b.srcID
	LEFT OUTER JOIN @TableC c
	  ON b.dstID = c.issueid
	  AND c.status <> 'Cancelled'
 GROUP BY a.id

Using the LEFT OUTER JOIN will still allow rows which do not have a match to be returned, if there were no rows in @TableB for a.id = b.srcID for example, they would still be returned, but the SUM of the NULLs would be NULL.

As an aside, it's a good habit to use consistent casings for your object names. There's some you've named with an upper case ID and others where it's a lower case id.