Ive been trying to sync the wallet for about a week and been watching it jump back and forward on sync loading bar.
This has also been my experience with BBK several times so far. However, the situation would correct itself if I left the wallet to sync long enough (read: days).
There's a bootstrap package available for download on the github download page, perhaps it could aid you in syncing:
https://github.com/BitBlocksProject/BitBlocks/releases/download/3.0.1/Blockchain.06-17-2018.08.45.GMT.-3.zipAnd pasting from offical announcement in discord channel: Extract this file into the bitblocks folder (%appdata% bitblocks) Always make a backup before changing this folder.
HTH