Unfortunately, yes.
Flickr made a change (~ 14 September 2016) which resulted in all Flash-based applications (not just TiltViewer) being unable to receive data via their API and, thus, display Flickr images.
Although no announcement was made by Flickr at the time (as far as I am aware), this change appears to have been intentional and not just a temporary glitch or bug.
In addition to Flash-based applications being unable to display Flickr images, TiltViewer-Pro was officially retired (back in mid 2015) and there will be no more updates (although an update would not have been able to solve the Flickr problem anyway).
TiltViewer-Standard (the free version) is still available for download (from this web page) but we discontinued and stopped selling TiltViewer-Pro in June 2015 (as noted on the TiltViewer-Pro home page).

Flash is undeniably on its way out and I would encourage anyone looking for an alternative image viewer to check out our HTML web gallery Juicebox.