I deleted the old data.mdb (not replace). When restart derod.exe, It's start to sync from begining...
but... Doesn't finish (still remain about 205 block). Will try with replace data.mdb.
(This is means every new DERO QT wallet will face the same problem )
solution with replacing data.mdb works for me, btw I also deleted old lock.mdb , which was not mentioned.
agree that problem with the sync needs to be investigated further. what surprise me that different nodes return different last block, maybe this causes some collisions.