After updating Alteryx Server from 2018.2 to 2019.2 we lost access to our Collections:

When click on one of them we get a 'page not found' message:

I also cannot remove and re-add them again, nor create new Collections:

The workflows do still exist in the Private Studio and those workflows that were publish Gallery-wide are also still there.
Anyone experienced this as well and managed to resolve it?
Regards,
Ruben