I get this bug, would be good to see it fixed as for my game I will need to change Natspread.

I had this problem aswell, wasted hours making a good schedule only to lose it by changing the natspread, had the exact same problem, game loads then you save and it wont reload after saving.

program files/so5/data/1/_sched_f

Open that file with notepad after saving you edited schedule, the numbers are at the top, you need to match them up with your schedule

none = 0
half = 1
normal = 2
x2 = 3
x3 = 4
x4 = 5
x5 = 6

the first letter x always stays the same for uk

you might have to redo it after a new patch, I had to after the last one.

Which would be better for a US only flat schedule (1 or 2 races in a few countries)
natSpread:1,x,1,1,1,1,1,1,1,1,1
or would one of these be better to get larger fields in races?
natSpread:0,x,0,0,0,0,0,0,0,0,0
natSpread:0,0,0,0,0,0,0,0,0,0,0