It worked correctly for me.
How I tested it.
I created a brand new FMP 13 file in Windows 7 using FMP 13 Advanced 13.0v3. I defined a calculation field named "TextBlock" with text as the result type as a way to generate text with all of the above characters:
" " & "A" & Char (13) & "B" & Char (8) & "C" & Char (9) & "D" & Char (10)
I then defined a second calculation field with a "text" result type:
Substitute (TextBlock ; [" " ; ""] ; [Char (13) ; ""] ; [Char (8) ; ""] ; [Char (9); ""] ; [Char (10) ; ""])
With all of the added characters stripped out by the substitute function, I should just get the letters ABCD and that was the result returned by the function.
I then returned to manage | Database and modified TextBlock by adding many more instances of the Char and quoted space characters plus the letter "Z" as the final character.
The resulting value: ABCDZ
This would be the exact value expected.
At the end of my testings even the plain Substitute(" " ; "") was showing empty result when i used in on several texts taken from several webpages (source code). The same was working on another mashcines, same OS, Same FM Version 13.03
Yesterday i updated again my FM Advanced 13.03 using the 13.03 Updater and now everything work normal again (as it was before).