2.4.3 out but cant multibox the 64bit client

[NetQvist]

I know the dev version of innerspace said it had added support for the Diablo PTR version, have you tried that? The option is somewhere inside innerspace, just tick it and it will download it.

EDIT: Saw that you posted on the IsBoxer forum as well

For anyone else it's a known issue and Lax (Author of IsBoxer) is working on it.