SQL Server could not produce query plan while querying view containing reference to External Table

Question

Hello, I have the following problem. Hopefully somebody can help me with it.

Error given back by SQL server:
Msg 8624, Level 16, State 1, Line 1
Internal Query Processor Error: The query processor could not produce a query plan. For more information, contact Customer Support Services.

Situation:

• Two databases on one Azure Database server, one called sqldb-DWH and the other called sqldb-Prepared
• Table in sqldb-Prepared named [dbo].[Ticket_tmp]
• External Table in sqldb-DWH called [dbo].[Ticket_tmp] referencing [sqldb-Prepared].[dbo].[Ticket_tmp]
• View referencing this External Table

Since I had issues adding attachment, see below section ObjectDefinitions for the exact definition of mentioned objects. The table [sqldb-Prepared].[dbo].[Ticket_tmp] is only filled with INT values 1 up through 5 (so 5 records)

Issue:

When performing the following query on the view the error occurs:
SELECT [TicketNo] ,[TicketType] FROM [dbo].[vw_Ticket_tmp] WHERE [TicketType] = 'Something' (or likewise when [TicketType = 'SomethingElse')

When the whole list of possible values of [TicketType] is provided, no error occurs. This can be acchieved either two ways:
SELECT [TicketNo] ,[TicketType] FROM [dbo].[vw_Ticket_tmp] (so removal of WHERE clause)
or
SELECT [TicketNo] ,[TicketType] FROM [dbo].[vw_Ticket_tmp] WHERE [TicketType] IN ('Something', 'SomethingElse') (so inclusion of all possible values in WHERE clause)

This only seems to be the case for putting a WHERE clause on the field that was manually added in the view, in this case [TicketType]. For example the following does not returns the error:
SELECT [TicketNo] ,[TicketType] FROM [dbo].[vw_Ticket_tmp] WHERE [TicketNo] = 3

ObjectDefinitions

-- Database: sqldb-Prepared --

/****** Object: Table [dbo].[Ticket_tmp] Script Date: 10-12-2021 11:24:44 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Ticket_tmp](
[TicketNo] [int] NULL
) ON [PRIMARY]
GO

INSERT INTO [dbo].[Ticket_tmp] VALUES (1), (2), (3), (4), (5)

-- Database: sqldb-DWH --

/****** Object: Table [dbo].[Ticket_tmp] Script Date: 10-12-2021 11:24:08 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER OFF
GO
CREATE EXTERNAL TABLE [dbo].[Ticket_tmp]
(
[TicketNo] [int] NULL
)
WITH (DATA_SOURCE = [Prepared],SCHEMA_NAME = N'dbo',OBJECT_NAME = N'Ticket_tmp')
GO
/****** Object: View [dbo].[vw_Ticket_tmp] Script Date: 10-12-2021 11:24:08 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE VIEW [dbo].[vw_Ticket_tmp] AS

SELECT [TicketNo]
,[TicketType] = 'Something'
FROM [dbo].[Ticket_tmp]

UNION

SELECT [TicketNo]
,[TicketType] = 'SomethingElse'
FROM [dbo].[Ticket_tmp]
GO

Thanks in advance!
Justin