Have the same issue with vSphere 6.7U1. ESXi Hosts are all patched with 11675023. No errors displayed in my case, just the deployment of OVF fails.
Cannot deploy any .OVF files with either the FLEX or HTML5 interface. This issue is made worse by the fact that my associated NSX 6.4.4 instance cannot deploy and ESGs because again this fails at the deployment of the OVF!
Using the ESXi web interface allows successful deployment of an OVF but this doesn't help me with NSX!.