That, I think, will be due to a bug in the 3.x MODX parser.
@halftrainedharry has posted a fix for that issue here.
However, even after applying that fix, I still see [what I think are] MODX tag parsing issues when adding output modifiers to the template chunks.
I still think it should be possible with pdoMenu but have hit a wall for now.
BTW - from my previous code …
[[+id:isnot=`8`
… isn’t quite right as we should be checking against the top-level parent of the current ID - not the ID itself.
Not sure I’ve helped much, sorry!