FortiClient 6.4.1 does not work with SAML but 6.4.0 does

Is the fact that SAML doesn't work in 6.4.1 a known bug and are there any workarounds or plans to resolve this? Alternatively is this just me?

In our testing across a number of machines FortiClient 6.4.0 connects without issues, but 6.4.1 aborts at about 50%.

Apologies if this has already been posted elsewhere, I did try and search before posting.