Currently on my save file, Euclides Belt only loads from the halfway checkpoint whenever you click "Mission Start". After trying multiple solutions (rebooting the game, finishing the level and trying to start it again, selecting "restart mission", etc) the game continues to load Euclides belt from the halfway point. the cause of this bug is unknown, but as there are currently no save file options for this game (as of ver 0.6.21), the Euclides Belt checkpoint skip will be legal for any%.

This bug was patched out, the developer stated they had forgotten to set the correct start point for the map as they were doing testing. The 0.6.21 19:05 Any% run will soon be archived/hidden on the official leaderboard to reflect this change

Is there more content now than 11 months ago, is the rotating boss you're talking about at the end of the pyramid level?

There is likely much more content in the game now, I havent played in awhile. This skip was on version 0.6.21 for the stage Euclides Belt, it was patched out a very long time ago