A bit of an update as I'm starting to suspect the weird pages is a bit of a technical glitch at Sedo.
I've not had any official response yet which is fair enough as the day hasn't really begun but I see some of the sites affected are now showing the usual branded Sedo parking pages with the for sale link etc. The only problem now is the templates are still not the ones selected in the optimizer. For instance I have long standing adult domains that have been running an adult template without change for months now showing with the "phoenix blue" template.
The good news is I feel a little more confident that I will get credited with any traffic that manages to find the domain.
I will see how things progress today and report back if I hear or experience anything more.