A few days ago, I took the Mountain Lion plunge and after performing all the preliminary data copying to external hard drives as well as on last Time Machine backup to my dedicated Time Machine external hard drive, I booted from my ML recovery USB thumb drive, reformatted the internal HD, and proceeded to perform a clean install of OS X 10.8.
The ML install and initial setup completed without a hitch, and I had no difficulty in reconnecting to my existing Time Machine EHD and performing an initial backup of the freshly upgraded Mountain Lion system. It took several minutes in the "preparing backup" phase; but once it got through that, it backed up my entire system (which was basically nothing more than the new OS and iLife at this point) within an hour or so. Time Machine has since worked reliably in performing the automatic backups every hour.
But here's the problem: My backup history went back all the way to March 2011 before the ML upgrade, and it still (sorta kinda) does now. However, although I can see all of the backup history tick marks when I enter TM, the ONLY SELECTABLE backups are from the point where ML was installed and onward. The previous Lion and Snow Leopard backups are visible; just not selectable. I also verified that the physical backup folders are still present on my TM EHD dating all the way back to last March. I ran a verify and repair operation on the TM volume, and it came back clean. I have disconnected and reconnected the TM EHD to TM and of course rebooted, but no joy. TM did not force me to "start over" with a new backup as some posters have complained of. And it seems to be working fine otherwise.
Has anyone else had a similar experience after upgrading to ML? Any thoughts on how I might reconnect to my TM backup history?
Thanks in advance for your thoughts.