Well after logging out my user in UM and logging in again, it is almost like Chrome lost all cookies that kept me logged into forums like this e.g. Firefox works properly though.
I tried starting Chrome from the terminal to see if I would get any helpful error messages, but I don't know if these are due to the fact that I get logged out from my Google account too:
[32222:32284:1105/183926:ERROR:gcm_store_impl.cc(922)] Failed to restore security token.
[32222:32222:1105/183926:ERROR:account_tracker.cc(357)] OnGetTokenFailure: Not authorized.