I upgraded recently to VCSA 6.7 U3 and have an issue with the Update Manager.
I download the patches from an Update Manager Download Service repository.
When I download patches the system returns a successful status for the download but the patch list remains empty.
I ran DB reset on the VCSA as per VMware KB 2147284 to no effect.
Importing offline update packages works.
I haven't found any online notes regarding this issue.
I'm hoping someone has come across it.
It is not indicated which browser you are connecting to, but it is known that version 6.7 U3 has some problems with Firefox:
In case you are using Firefox, try changing your browser and let's see if it improves.
P.S: just to clarify: the error indicated in the link (below) is not the same but considering that Firefox has some problems with Update manager 6.7 U3 (only your aversion) it is worth trying with another browser if not already you have done.