Hello.
In order to get the necessary information that we need to troubleshoot this I will need to ask you for some extra information. This requires some extra steps
1. Have the host right click on Hearts of Iron in Steam
2. Click properties
3. In the launch options write "-light_random_log" without the ""

4. Host the game as normal, have people join
5. When you OOS everyone will get a white text saying something like "OOS_N/Y_number_blablabla", when you get this just have everyone wait until it is finished. Dont click on anything
6. Check which check person or persons oosed, this should be visible in the text that says "X player is no longer in sync"
7. Have the persons which OOSED AND the host go to C:\Users\USERNAME\Documents\Paradox Interactive\Hearts of Iron IV\oos
8. In there you will find a zip folder, if you are a client it will look like this
if it is a host it will look like this

9. Grab these oos folders from both the one who oosed and the host of the server and upload them here
These folders contain necessary information that we need in order to figure out whats going on.
I know it a bit of a hassle but it really helps us
In order to get the necessary information that we need to troubleshoot this I will need to ask you for some extra information. This requires some extra steps
1. Have the host right click on Hearts of Iron in Steam
2. Click properties
3. In the launch options write "-light_random_log" without the ""
4. Host the game as normal, have people join
5. When you OOS everyone will get a white text saying something like "OOS_N/Y_number_blablabla", when you get this just have everyone wait until it is finished. Dont click on anything
6. Check which check person or persons oosed, this should be visible in the text that says "X player is no longer in sync"
7. Have the persons which OOSED AND the host go to C:\Users\USERNAME\Documents\Paradox Interactive\Hearts of Iron IV\oos
8. In there you will find a zip folder, if you are a client it will look like this
if it is a host it will look like this
9. Grab these oos folders from both the one who oosed and the host of the server and upload them here
These folders contain necessary information that we need in order to figure out whats going on.
I know it a bit of a hassle but it really helps us