well I resynced and my last block is 34929
I see a similar problem, my 3 sancs reorged back to 34929 when these 20 new nodes came online.
Let me explain to everyone one conundrum (this affects Dash also). The sancs must be online in order for our daily superblock consensus to work, and for masternode payments to work (as their vote heights must be exact and correct), and the sancs go out of sync when the supermajority of the miners reorganize (meaning they need Re-Enabled manually). While they are not enabled, the entire network is really just free-riding. Its that chicken and egg issue I explained earlier.
Once the sancs are enabled while they are at a similar height as the supermajority things should clear up.
Right now all sancs are out of sync and disabled.