in the scenario editor, if i start the stopped time...

Error while running event fcpu::on_tick (ID 0)
fcpu/src/utils/Heap.lua:74: attempt to index local 'h' (a nil value)
stack traceback:
fcpu/src/utils/Heap.lua:74: in function 'priority'
fcpu/src/cpu/controller.lua:249: in function 'do_deferred'
fcpu/control.lua:101: in function <fcpu/control.lua:86>

I just found out that scenario migrations have to be handled completely separately from regular saves. Sorry for this.
Should be fixed in v0.4.63

I think your previous issue with the scenario might also be related to the fact that the migrations simply weren’t applied, which resulted in a state I couldn’t reproduce on my side.

Yes, I already thought that things work differently in the scenario editor. I can only work normally with the fcpu there when the time is running. It doesn't work in pause mode. Thanks for the quick fix.