Spain '37 event occurence

[unmerged(22760)]

Hi,

First I thought that the incidence of spanish '37 event , the one with Barcelona revolting and change of government, is almost every time.
My last 10 times I've played as Republican Spain, it didn't happened at all.
Are there any special condition for it, beside the ones listed in the event file = no more Nat. Spain and government no communist ?

Please help as this has ruined a lot of my games.

 

[unmerged(22760)]

no answers at all ?

 

[unmerged(22760)]

At least I did experiments and came to the conclusion that:
1. Being or not in an alliance with England doesn't influence
2. Ending date of war with Nat Spain, assuming it happened before 03/05/37, and by annexing them. First I thought that war must end in '37, but can end also in '36, and that event trigger.
3. Internal policy sliders setting, especially the 'interventionism' one.

Therefore I must assume that is only the 7% of random chances that influence.