I am receiving a:

Conversion failed when converting from a character string to uniqueidentifier

error when I attempt to UNION ALL two identical queries that have been wrapped in subqueries. I am not sure what this is referring to since the queries work fine individually. Could it be the syntax?

SELECT * 
FROM (
        SELECT 
            Table1.[Owner]
        FROM
            (
            SELECT
                owneridname [Owner], 
                incidentid [Ticket Number1]
                FROM
                    incident
            ) as Table1

            LEFT JOIN

            (
                SELECT
                    MAX(DATEADD(hh,-7,svb_timestamp)) [Time Stamp],
                    svb_caseid [Ticket Number2]
                FROM
                    svb_caseupdate
                GROUP BY svb_caseid
            ) as Table2
         ON Table1.[Ticket Number1] = Table2.[Ticket Number2]
) sq1
         
UNION ALL

SELECT *
FROM (
         SELECT 
            Table1.[Owner]
         FROM
            (
            SELECT
                svb_cssowner [Owner], 
                incidentid [Ticket Number1]
                FROM
                    incident
            ) as Table1

            LEFT JOIN

            (
                SELECT
                    MAX(DATEADD(hh,-7,svb_timestamp)) [Time Stamp],
                    svb_caseid [Ticket Number2]
                FROM
                    svb_caseupdate
                GROUP BY svb_caseid
            ) as Table2
         ON Table1.[Ticket Number1] = Table2.[Ticket Number2]
) sq2

I was expecting to append both tables together which should be fairly simple.