@Dominik Hoefling I am using Seamless SSO with PTA. I downloaded the Chrome ADMX files and configured Kerberos delegation server whitelist and Authentication server white list adding autologon.microsoftazuread-sso.com to both.
I haven't any problems with PTA and AAD Seamless SSO (I'm using Chrome for Windows Version 75.0.3770.142). I would suggest to run Fiddler and verify if the browser get the 401 unauthorized response from Azure AD, to provide a Kerberos ticket.
I assume that modern authentication is enabled in Exchange Online (this is a prerequisite).
@Dominik Hoefling I didn't have modern authentication turned on however I did that last night. Still not any better. I have looked through that documentation and nothing jumps out. Also, it is quite out dated with certain things. One "big" thing is that Edge doesn't work when actually now it does.
I think Fiddler is a good call. I will give that a bash