I've opened SR yesterdy but no answer yet. I'm not sure which logs to provide.
No problem with this VMware vSphere Web Client before (deploying VDP and update to VCSA 5.1.0.5200 Build 880472). I've tried to use FireFox instead of Chromium browser but with the same result.
I installed last build of VCSA on standalone ESXi. No success using vSphere Web Client (the same problem with deploying OVA file). In the end I used vSphere Client I'm using to access VUM and I got through. The same way I was able to deploy vSphere Replication then.
It looks like some vSphere Web Client problem. I'll try to deploy vSphere Replication in bew installed VCSA to confirm it.