If this SMBX2.0.0 Beta 4 exclusive custom level is a mixed of Super Mario Bros. 1 & Super Mario Bros.Special, then did you make this level multi-sectional?
Be sure to red the description. It has only been a few days since my PC has been working again, so I just wanted to get something out quickly to celebrate the 35th anniversary before October, so that explains why the level is he way it is.
I didn't get this error when trying the level. Although the level has been updated. 2 firebars have been shortened because they were almost impossible to avoid due to rotating faster than they should in SMBX, as well as fixing a couple of issues with firebars in the final battle of the level.