If you create a post that contains BBCode as this

[color=#BF0000][b]SomeText[/b][/color]

and then search for "SomeText" it will not be found.

If you add "SomeText" into the same post as normal text and then search it will find, and highlight, both text entries.

If you enter

[b]SomeText[/b]

Then there is no problem with the search - it will be found.

Not sure if this may be something to do with the combination of text highlighting and the use of the color BBCode