Flat pattern - SOLIDWORKS

Please for your appreciated help!
I got one position in STEP format that I need to convert as sheet metal, the position has a lot of radius. I manage to convert the position, but after the FLATEN order, only one small area "opens" to me, not the whole model. What could be the problem? I did not find a solution on YOUTUBE.
Many thanks to everyone for helping in advance!
Drazen
try to zoom out if possible.
Could you share the file?
Save the file in STEP format and open it in CATIA. Beyond tabs environments in start tab, there is something like "hill assistant". In this environment there are some tools that automatically search and find gaps and suggest solution for them. Good luck