sp_Blitz: Error with parameter @OutputType = 'markdown'

[jukkama]

Version of the script
Version 8.22, version date 20241019

What is the current behavior?
It returns only an error
Warning: Null value is eliminated by an aggregate or other SET operation.
Msg 9421, Level 16, State 1, Procedure sp_Blitz, Line 10347 [Batch Start Line 24]
XML parsing: line 233, character 203, illegal name character

If the current behavior is a bug, please provide the steps to reproduce.
Run procedure with this parameter
sp_Blitz @OutputType = 'markdown'

What is the expected behavior?
Nicely formatted list to use with email etc as it was in earlier script version

Which versions of SQL Server and which OS are affected by this issue? Did this work in previous versions of our procedures?
Problem faced with SQL Server 2019 (15.0.4360.2) in Windows Server 2019. This worked in script version 8.15, version date 20230613 on the same platform.

[BrentOzar]

@jukkama sorry about that! Can you run sp_Blitz in regular mode, and look at what the difference is in output between the old & new versions? I'm guessing there's a new check between 8.22 and 8.15 that outputs something problematic on your server, but I can't see what that is from here.

[jukkama]

Here is the output difference without any parameters

Only in new version:
Priority FindingsGroup Finding ...
100 Performance Many Plans for One Query

Only in old version:
Priority FindingsGroup Finding
0 Outdated sp_Blitz sp_Blitz is Over 6 Months Old

In both but different:
Priority FindingsGroup Finding
0 sp_Blitz Oct 19 2024 12:00AM SQL Server First Responder Kit
0 sp_Blitz Jun 13 2023 12:00AM SQL Server First Responder Kit

[BrentOzar]

Hmm, none of that has illegal XML characters, so I'm guessing the princess we're looking for is in another castle.