Why private corps are disappearing? (Little Upsilon)

i have my main country set 0% tax for corps, im trying to get more than 100 pvt corps in that country, every time when i finally get 104- 106 pvt corps, 3 or 5 of them disappear. that has happened to me about 5 times. yesterday i had 105 pvt corps, today i have 100.
there are severals reasons why ceo's decide to move their corps from one country to other. one of them is because of the tax, which i dont think is my case cuz i have set 0%. other reason is because he or she may decide to close the corps because its not profitable,which i dont think is the reason cuz this problem has happened to me not 1 but 5 times.
any idea what is going on with this problem? thnks

The other likely cause is if you're having population issues, CEO's are likely to abandon ship to better managed countries. However, I've never noticed any issues in your countries, and, as a CEO, have been happy with being in your countries. I wish you could get a notification when someone moved their company out. (a) You could find out what you were doing wrong to fix it for the next CEO, and (b) you'd know there was a CEO vacancy available for new companies.