1. 1 Not a question, just a remark
I noticed, after have made some tests, that RuleSet may have a big impact on UFO fullfilment
For example, supposed UFO has 10 available nodes (i.e. Spawn set to 1)
Whatever type you set for any of nodes, if you declare in ruleset :
10 Soldiers, 0%outside
all will be soldiers
10 Engineers, 0%outside
all will be engineers
10 Soldiers, 0%outside first
10 Engineers, 0% outside then
10 Engineers, 0%outside first
10 Soldiers, 0% outside then 1

2. (2:Spawn, 3:Spawn, …, 10:Spawn)
I did not understand what is use of « Spawn » attribute value if different from 0 or 1
(2:Spawn, 3:Spawn, …, 10:Spawn)
Do you have any idea ? 2

3. It is same for some UFOs you created
In standard Large Scout, no node with « Spawn » attribute set to 0-NoSpawn
It is same for some UFOs you created
Regarding RuleSet, in case of setting up number of aliens to 21 or more, with %outside set to 0, all nodes will be filled in, and alien will not move 3

4. create more nodes with attribute Spawn set to 0:No Spawn
Proposition
create more nodes with attribute Spawn set to 0:No Spawn
Example beside
(certainly not so many, just some to allow aliens to move, and, if possible, hide themselves)
I made a test (XCOM units set to supermen with 250 of movement and so on, aliens set to wear no weapons, …) and this seems to work well 3

5. Could you provide me :
All standard files (routes, terrain, …) so I am sure to work on a same version as you
Your custom files if updated
A list of 3 UFOS you would like I begin to deal with 4