I'm pretty sure I'm late on this ... but I'll answer anyway (in case someone else is looking for the same issue): in my case, I needed to specify Chassis Connection Policy to "none", while the global policy was "port-channel" since the UCS domain already had some 5108 chassis and HX systems as well.
As soon as the Chassis Connectivity Policy has been corrected (only for the S3260 chassis) the service profile was correctly associated and vHBAs were created as expected.
Please notice that in my case we had two SIOCs and two servers for each S3260 chassis (you may have different configurations and/or connectivity needs).